Method and system for providing quality-of-service in a data-over-cable system

ABSTRACT

A method and system for quality-of-service in a data-over-cable system is provided. A cable modem in a data-over-cable system makes a connection request to a cable modem termination system with a requested quality-of-service. The requested quality-of-service includes class-of-service, quality-of-service and other related parameters. The connection request is sent from a cable modem or a cable modem termination system to a Quality-of-Service (“QoS”) server. The OoS server determines if the cable modem termination system has enough bandwidth to make the connection to the cable modem with the requested quality-of-service. If the cable modem termination system has enough bandwidth, a quality-of-service identifier is to returned to the cable modem termination system. The cable modem termination system uses the quality-of-service identifier to make a connection to the cable modem with the requested QoS to the cable modem. The QoS server reduces the computational burden and complexity of software on the cable modem termination system. The QoS server is flexible and adaptable to new QoS parameters and provides a standard way to balance QoS requests among multiple cable modem termination systems.

FIELD OF INVENTION

The present invention relates to communications in computer networks.More specifically, it relates to a method and system for providingquality-of-service to a cable modem in a data-over-cable system.

BACKGROUND OF THE INVENTION

Cable television networks such as those provided by Comcast CableCommunications, Inc., of Philadelphia, Pa., Cox Communications ofAtlanta Ga., Tele-Communications, Inc., of Englewood Colo. Time-WarnerCable, of Marietta Ga., Continental Cablevision, Inc., of Boston Mass.,and others provide cable television services to a large number ofsubscribers over a large geographical area. The cable televisionnetworks typically are interconnected by cables such as coaxial cablesor a Hybrid Fiber/Coaxial (“HFC”) cable system which have data rates ofabout 10 Mega-bits-per-second (“Mbps”) to 30+ Mbps.

The Internet, a world-wide-network of interconnected computers, providesmulti-media content including audio, video, graphics and text thatrequires a large bandwidth for downloading and viewing. Most InternetService Providers (“ISPs”) allow customers to connect to the Internetvia a serial telephone line from a Public Switched Telephone Network(“PSTN”) at data rates including 14,400 bps, 28,800 bps, 33,600 bps,56,000 bps and others that are much slower than the about 10 Mbps to 30+Mbps available on a coaxial cable or HFC cable system on a cabletelevision network.

With the explosive growth of the Internet, many customers have desiredto use the larger bandwidth of a cable television network to connect tothe Internet and other computer networks. Cable modems, such as thoseprovided by 3Com Corporation of Santa Clara, Calif., MotorolaCorporation of Arlington Heights, Ill., Hewlett-Packard Co. of PaloAlto, Calif. Bay Networks of Santa Clara, Ca., Scientific-Atlanta, ofNorcross, Ga. and others offer customers higher-speed connectivity tothe Internet, an intranet, Local Area Networks (“LANs”) and othercomputer networks via cable television networks. These cable modemscurrently support a data connection to the Internet and other computernetworks via a cable television network with a data rate of up to 30+Mbps which is a much larger data rate than can be supported by a modemused over a serial telephone line.

However, most cable television networks provide only unidirectionalcable systems, supporting only a “downstream” data path. A downstreamdata path is the flow of data from a cable system “headend” to acustomer. A cable system headend is a central location in the cabletelevision network that is responsible for sending cable signals in thedownstream direction. A return data path via a telephone network, suchas a public switched telephone network provided by AT&T and others,(i.e., a “telephony return”) is typically used for an “upstream” datapath. An upstream data path is the flow of data from the customer backto the cable system headend. A cable television system with an upstreamconnection to a telephony network is called a “data-over-cable systemwith telephony return.”

An exemplary data-over-cable system with telephony return includescustomer premise equipment (e.g., a customer computer), a cable modem, acable modem termination system, a cable television network, a publicswitched telephone network, a telephony remote access concentrator and adata network (e.g., the Internet). The cable modem termination systemand the telephony remote access concentrator together are called a“telephony return termination system.”

The cable modem termination system receives data packets from the datanetwork and transmits them downstream via the cable television networkto a cable modem attached to the customer premise equipment. Thecustomer premise equipment sends response data packets to the cablemodem, which sends response data packets upstream via public switchedtelephone network to the telephony remote access concentrator, whichsends the response data packets back to the appropriate host on the datanetwork.

When a cable modem used in the data-over-cable system with telephonyreturn is initialized, a connection is made to both the cable modemtermination system via the cable network and to the telephony remoteaccess concentrator via the public switched telephone network. As acable modem is initialized, it will initialize one or more downstreamchannels (i.e., downstream connections) to the cable modem terminationsystem via the cable network or the telephony remote access concentratorvia the public switched telephone network.

As a cable modem is initialized in a data-over-cable system, itregisters with a cable modem termination system to allow the cable modemto receive data over a cable television connection and from a datanetwork (e.g., the Internet or an Intranet). The cable modem forwardsconfiguration information it receives in a configuration file duringinitialization to the cable modem termination system as part of aregistration request message.

Configuration information forwarded to a cable modem termination systemfrom a cable modem includes Class-of-Service (“CoS”) andQuality-of-Service (“QoS”) and other parameters. As is known in the art,class-of-service provides a reliable (e.g., error free, in sequence,with no loss of duplication) transport facility independent of thequality-of-service. Class-of-service parameters include maximumdownstream data rates, maximum upstream data rates, upstream channelpriority, guaranteed minimum data rates, guaranteed maximum data rateand other parameters. Quality-of-service collectively specifies theperformance of a network service that a device expects on a network.Quality-of-service parameters include transit delay expected to deliverdata to a specific destination, the level of protection fromunauthorized monitoring or modification of data, cost for delivery ofdata, expected residual error probability, the relative priorityassociated with the data and other parameters.

A cable modem termination system is responsible for providingclass-of-service and quality-of-service connections to a cable modem.However, there are several problems associated with using a cable modemtermination system to provide class-of-service and quality-of-serviceconnections to a cable modem. The cable modem termination system isresponsible for handling and balancing class-of-service andquality-of-service requests for tens of thousands of cable modems. Thehandling and balancing class-of-service and quality-of-service includesallocating bandwidth for guaranteed transmission rates requested by thecable modems. The handling and balancing requires significantcomputational and computer resources on the cable modem terminationsystem. The cable modem termination system uses complex software that isnot easily adaptable to new or additional class-of-service orquality-of-service parameters. In addition, multiple cable modemtermination systems in a data-over-cable systems do not handle orbalance class-of-service or quality-of-service parameters in a standardway. Thus, it is desirable to provide a standard, efficient and costeffective way to provide class-of-service and quality-of-service tocable modems in a data-over-cable system.

SUMMARY OF THE INVENTION

In accordance with a preferred embodiment of the present invention, theproblems associated with providing quality-of-service to a cable modemin a data-over-cable system are overcome. A system and method forproviding quality of service to a cable modem in a data-over-cablesystem is provided.

The system includes a quality-of-service server, for determining whethera first network device has enough available bandwidth to establish aconnection to a second network device with a specific quality-of-servicerequested by the second network device. The quality-of-service serverprovides support for class-of-service, quality-of-service and otherparameters. The system also includes multiple quality-of-serviceidentifiers, for identifying a transmission bandwidth required for aspecific quality-of-service requested by a second network device,wherein a value for a quality-of-service identifier is determined by thequality-of-service bandwidth requested by class-of-service,quality-of-service and other parameters.

In a preferred embodiment of the present invention, the first networkdevice is a cable modem termination system and the second network deviceis a cable modem. However, the present invention is not limited to thesenetwork devices and other network devices could also be used.

The method includes receiving a request on a first network device from asecond network device to establish a connection between the secondnetwork device and a third network device with a specificquality-of-service requested by the third network device. The firstnetwork device determines whether the second network device has enoughavailable bandwidth to establish the connection to the third networkdevice with the specific quality-of-service requested by the thirdnetwork device. The quality-of-service request includes class-of-serviceand quality-of-service parameters. If the first network device hasenough bandwidth to establish the connection to the third network devicewith the specific quality-of-service desired by the third networkdevice, a bandwidth required for the specific quality-of-servicerequested by the third network device is subtracted from an availablebandwidth for the second network device. The bandwidth required includesbandwidth for the requested class-of-service and quality-of-serviceparameters. A quality-of-service identifier is assigned to the specificquality-of-service bandwidth requested by the third network device. Theassigned quality-of-service identifier is saved on the first networkdevice. The assigned quality-of-service identifier is sent to the secondnetwork device indicating the second network device has enough bandwidthto allow the connection with the specific quality-of-service requestedby the third network device.

In a preferred embodiment of the present invention, the first networkdevice is a quality-of-service server, the second network device is acable modem termination system and the third network device is a cablemodem. The quality-of-service server provides support forquality-of-service, class-of-service, and other parameters, but iscalled a “quality-of-service server” for the sake of simplicity.However, the present invention is not limited to these network devicesand other network devices could also be used.

A preferred embodiment of the present invention offers severaladvantages over the prior art. A preferred embodiment of the presentinvention allows class-of-service and quality-of-service to be handledand balanced in a data-over-cable system by a quality-of-service server.This relieves the computational burden from the cable modem terminationsystem and helps reduce or eliminate the need for complexclass-of-service and quality-of-service software on the cable modemtermination system. The class-of-service server provides a standardizedway of handling class-of-service and quality-of-service requests and iseasily adaptable for new class-of-service or quality-of-serviceparameters.

The foregoing and other features and advantages of a preferredembodiment of the present invention will be more readily apparent fromthe following detailed description, which proceeds with references tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a cable modem system withtelephony return;

FIG. 2 is a block diagram illustrating a protocol stack for a cablemodem;

FIG. 3 is a block diagram illustrating a Telephony Channel Descriptormessage structure;

FIG. 4 is a block diagram illustrating a Termination System Informationmessage structure;

FIG. 5 is a flow diagram illustrating a method for addressing hosts in acable modem system;

FIG. 6 is a block diagram illustrating a Dynamic Host ConfigurationProtocol message structure;

FIGS. 7A and 7B are a flow diagram illustrating a method for discoveringhosts in a cable modem system;

FIG. 8 is a block diagram illustrating a data-over-cable system for themethod illustrated in FIGS. 7A and 7B;

FIG. 9 is a block diagram illustrating the message flow of the methodillustrated in FIGS. 7A and 7B;

FIGS. 10A and 10B are a flow diagram illustrating a method for resolvinghost addresses in a data-over-cable system;

FIG. 11 is a flow diagram illustrating a method for resolving discoveredhost addresses; and

FIG. 12 is a block diagram illustrating the message flow of the methodillustrated in FIG. 10;

FIGS. 13A and 13B are a flow diagram illustrating a method for obtainingaddresses for customer premise equipment;

FIGS. 14A and 14B are a flow diagram illustrating a method for resolvingaddresses for customer premise equipment;

FIGS. 15A and 15B are a flow diagram illustrating a method foraddressing network host interfaces from customer premise equipment;

FIGS. 16A and 16B are a flow diagram illustrating a method for resolvingnetwork host interfaces from customer premise equipment;

FIG. 17 is a block diagram illustrating a message flow for the methodsin FIGS. 15A, 15B, and 16A and 16B;

FIG. 18 is a block diagram illustrating data-over-cable system with aquality-of-service server;

FIG. 19 is a flow diagram illustrating a method for providingquality-of-service for a network device in a data over-cable-system;

FIG. 20 is flow diagram illustrating a method for providingquality-of-service to a cable modem;

FIG. 21 is a flow diagram illustrating a method for determiningquality-of-service from a network device; and

FIG. 22 is a flow diagram illustrating a method for determiningquality-of-service from a cable modem termination system.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Cable Modem System WithTelephony Return

FIG. 1 is a block diagram illustrating a data-over-cable system withtelephony return 10, hereinafter data-over-cable system 10. Most cableproviders known in the art predominately provide unidirectional cablesystems, supporting only a “downstream” data path. A downstream datapath is the flow of data from a cable television network “headend” tocustomer premise equipment (e.g., a customer's personal computer). Acable television network headend is a central location that isresponsible for sending cable signals in a downstream direction. Areturn path via a telephony network (“telephony return”) is typicallyused for an “upstream” data path in uni-directional cable systems. Anupstream data path is the flow of data from customer premise equipmentback to the cable television network headend.

However, data-over-cable system 10 of the present invention may alsoprovide a bi-directional data path (i.e., both downstream and upstream)without telephony return as is also illustrated in FIG. 1 and thepresent invention is not limited to a data-over-cable system withtelephony return. In a data-over cable system without telephony return,customer premise equipment or cable modem has an upstream connection tothe cable modem termination system via a cable television connection, awireless connection, a satellite connection, or a connection via othertechnologies to send data upstream to the cable modem terminationsystem.

Data-over-cable system 10 includes a Cable Modem Termination System(“CMTS”) 12 connected to a cable television network 14, hereinaftercable network 14. FIG. 1 illustrates one CMTS 12. However,data-over-cable system 10 can include multiple CMTS 12. Cable network 14includes cable television networks such as those provided by ComcastCable Communications, Inc., of Philadelphia, Pa., Cox Communications, orAtlanta, Ga., Tele-Communications, Inc., of Englewood Colo., Time-WarnerCable, of Marietta, Ga., Continental Cablevision, Inc., of Boston,Mass., and others. Cable network 14 is connected to a Cable Modem (“CM”)16 with a downstream cable connection. CM 16 is any cable modem such asthose provided by 3Com Corporation of Santa Clara, Calif., MotorolaCorporation of Arlington Heights, Ill., Hewlett-Packard Co. of PaloAlto, Calif., Bay Networks of Santa Clara, Calif., Scientific-Atlanta,of Norcross, Ga. and others. FIG. 1 illustrates one CM 16. However, in atypical data-over-cable system, tens or hundreds of thousands of CM 16are connected to CMTS 12.

CM 16 is connected to Customer Premise Equipment (“CPE”) 18 such as apersonal computer system via a Cable Modem-to-CPE Interface (“CMCI”) 20.CM 16 is connected to a Public Switched Telephone Network (“PSTN”) 22with an upstream telephony connection. PSTN 22 includes those publicswitched telephone networks provided by AT&T, Regional Bell OperatingCompanies (e.g., Ameritch, U.S. West, Bell Atlantic, Southern BellCommunications, Bell South, NYNEX, and Pacific Telesis Group), GTE, andothers. The upstream telephony connection is any of a standard telephoneline connection, Integrated Services Digital Network (“ISDN”)connection, Asymmetric Digital Subscriber Line (“ADSL”) connection, orother telephony connection. PSTN 22 is connected to a Telephony RemoteAccess Concentrator (“TRAC”) 24. In a data-over cable system withouttelephony return, CM 16 has an upstream connection to CMTS 12 via acable television connection, a wireless connection, a satelliteconnection, or a connection via other technologies to send data upstreamoutside of the telephony return path. An upstream cable televisionconnection via cable network 14 is illustrated in FIG. 1.

FIG. 1 illustrates a telephony modem integral to CM 16. In anotherembodiment of the present invention, the telephony modem is a separatemodem unit external to CM 16 used specifically for connecting with PSTN22. A separate telephony modem includes a connection to CM 16 forexchanging data. CM 16 includes cable modems provided by the 3ComCorporation of Santa Clara, Calif., U.S. Robotics Corporation of Skokie,Ill., and others. In yet another embodiment of the present invention, CM16 includes functionality to connect only to cable network 14 andreceives downstream signals from cable network 14 and sends upstreamsignals to cable network 14 without telephony return. The presentinvention is not limited to cable modems used with telephony return.

CMTS 12 and TRAC 24 may be at a “headend” of cable system 10, or TRAC 24may be located elsewhere and have routing associations to CMTS 12. CMTS12 and TRAC 24 together are called a “Telephony Return TerminationSystem” (“TRTS”) 26. TRTS 26 is illustrated by a dashed box in FIG. 1.CMTS 12 and TRAC 24 make up TRTS 26 whether or not they are located atthe headend of cable network 14, and TRAC 24 may in located in adifferent geographic location from CMTS 12. Content severs, operationsservers, administrative servers and maintenance servers used indata-over-cable system 10 (not shown in FIG. 1) may also be in differentlocations. Access points to data-over-cable system 10 are connected toone or more CMTS's 12 or cable headend access points. Suchconfigurations may be “one-to-one”, “one-to-many,” or “many-to-many,”and may be interconnected to other Local Area Networks (“LANs”) or WideArea Networks (“WANs”).

TRAC 24 is connected to a data network 28 (e.g., the Internet or anintranet) by a TRAC-Network System Interface 30 (“TRAC-NSI”). CMTS 12 isconnected to data network 28 by a CMTS-Network System Interface(“CMTS-NSI”) 32. The present invention is not limited to data-over-cablesystem 10 illustrated in FIG. 1, and more or fewer components,connections and interfaces could also be used.

Cable Modem Protocol Stack

FIG. 2 is a block diagram illustrating a protocol stack 36 for CM 16.FIG. 2 illustrates the downstream and upstream protocols used in CM 16.As is known in the art, the Open System Interconnection (“OSI”) model isused to describe computer networks. The OSI model consists of sevenlayers including from lowest-to-highest, a physical, data-link, network,transport, session, application and presentation layer. The physicallayer transmits bits over a communication link. The data link layertransmits error free frames of data. The network layer transmits androutes data packets.

For downstream data transmission, CM 16 is connected to cable network 14in a physical layer 38 via a Radio Frequency (“RF”) Interface 40. In apreferred embodiment of the present invention, RF Interface 40 has anoperation frequency range of 50 Mega-Hertz (“MHz”) to 1 Giga-Hertz(“GHz”) and a channel bandwidth of 6 MHz. However, other operationfrequencies may also be used and the invention is not limited to thesefrequencies. RF interface 40 uses a signal modulation method ofQuadrature Amplitude Modulation (“QAM”). As is known in the art, QAM isused as a means of encoding digital information over radio, wire, orfiber optic transmission links. QAM is a combination of amplitude andphase modulation and is an extension of multiphase phase-shift-keying.QAM can have any number of discrete digital levels typically including4, 16, 64 or 256 levels. In one embodiment of the present invention,QAM-64 is used in RF interface 40. However, other operating frequenciesmodulation methods could also be used. For more information on RFinterface 40 see the Institute of Electrical and Electronic Engineers(“IEEE”) standard 802.14 for cable modems incorporated herein byreference. IEEE standards can be found on the World Wide Web at theUniversal Resource Locator (“URL”) “www.ieee.org.” However, other RFinterfaces 40 could also be used and the present invention is notlimited to IEEE 802.14 (e.g., RF interfaces from Multimedia CableNetwork Systems (“MCNS”) and others could also be used).

Above RF interface 40 in a data-link layer 42 is a Medium Access Control(“MAC”) layer 44. As is known in the art, MAC layer 44 controls accessto a transmission medium via physical layer 38. For more information onMAC layer protocol 44 see IEEE 802.14 for cable modems. However, otherMAC layer protocols 44 could also be used and the present invention isnot limited to IEEE 802.14 MAC layer protocols (e.g., MCNS MAC layerprotocols and others could also be used).

Above MAC layer 44 is an optional link security protocol stack 46. Linksecurity protocol stack 46 prevents authorized users from making a dataconnection from cable network 14. RF interface 40 and MAC layer 44 canalso be used for an upstream connection if data-over-cable system 10 isused without telephony return.

For upstream data transmission with telephony return, CM 16 is connectedto PSTN 22 in physical layer 38 via modem interface 48. TheInternational Telecommunications Union-Telecommunication StandardizationSector (“ITU-T”, formerly known as the CCITT) defines standards forcommunication devices identified by “V.xx” series where “xx” is anidentifying number. ITU-T standards can be found on the World Wide Webat the URL “www.itu.ch.”In one embodiment of the present invention,ITU-T V0.34 is used as modem interface 48. As is known in the art, ITU-TV0.34 is commonly used in the data link layer for modem communicationsand currently allows data rates as high as 33,600 bits-per-second(“bps”). For more information see the ITU-T V0.34 standard. However,other modem interfaces or other telephony interfaces could also be used.

Above modem interface 48 in data link layer 42 is Point-to-PointProtocol (“PPP”) layer 50, hereinafter PPP 50. As is known in the art,PPP is used to encapsulate network layer datagrams over a serialcommunications link. For more information on PPP see InternetEngineering Task Force (“IETF”) Request for Comments (“RFC”), RFC-1661,RFC-1662 and RFC-1663 incorporated herein by reference. Information forIETF RFCs can be found on the World Wide Web at URLs “ds.internic.net”or “www.ietf.org.”

Above both the downstream and upstream protocol layers in a networklayer 52 is an Internet Protocol (“IP”) layer 54. IP layer 54,hereinafter IP 54, roughly corresponds to OSI layer 3, the networklayer, but is typically not defined as part of the OSI model. As isknown in the art, IP 54 is a routing protocol designed to route trafficwithin a network or between networks. For more information on IP 54 seeRFC-791 incorporated herein by reference.

Internet Control Message Protocol (“ICMP”) layer 56 is used for networkmanagement. The main functions of ICMP layer 56, hereinafter ICMP 56,include error reporting, reachability testing (e.g., “pinging”)congestion control, route-change notification, performance, subnetaddressing and others. Since IP 54 is an unacknowledged protocol,datagrams may be discarded and ICMP 56 is used for error reporting. Formore information on ICMP 56 see RFC-971 incorporated herein byreference.

Above IP 54 and ICMP 56 is a transport layer 58 with User DatagramProtocol layer 60 (“UDP”). UDP layer 60, hereinafter UDP 60, roughlycorresponds to OSI layer 4, the transport layer, but is typically notdefined as part of the OSI model. As is known in the art, UDP 60provides a connectionless mode of communications with datagrams. Formore information on UDP 60 see RFC-768 incorporated herein by reference.

Above the network layer are a Simple Network Management Protocol(“SNMP”) layer 62, Trivial File Protocol (“TFTP”) layer 64, Dynamic HostConfiguration Protocol (“DHCP”) layer 66 and a UDP manager 68. SNMPlayer 62 is used to support network management functions. For moreinformation on SNMP layer 62 see RFC-1157 incorporated herein byreference. TFTP layer 64 is a file transfer protocol used to downloadfiles and configuration information. For more information on TFTP layer64 see RFC-1350 incorporated herein by reference. DHCP layer 66 is aprotocol for passing configuration information to hosts on an IP 54network. For more information on DHCP layer 66 see RFC-1541 and RFC-2131incorporated herein by reference. UDP manager 68 distinguishes androutes packets to an appropriate service (e.g., a virtual tunnel). Moreor few protocol layers could also be used with data-over-cable system10.

CM 16 supports transmission and reception of IP 54 datagrams asspecified by RFC-791.

CMTS 12 and TRAC 24 may perform filtering of IP 54 datagrams. CM 16 isconfigurable for IP 54 datagram filtering to restrict CM 16 and CPE 18to the use of only their assigned IP 54 addresses. CM 16 is configurablefor IP 54 datagram UDP 60 port filtering (i.e., deep filtering). CM 16forwards IP 54 datagrams destined to an IP 54 unicast address acrosscable network 14 or PSTN 22. Some routers have security featuresintended to filter out invalid users who alter or masquerade packets asif sent from a valid user. Since routing policy is under the control ofnetwork operators, such filtering is a vendor specific implementation.For example, dedicated interfaces (i.e., Frame Relay) may exist betweenTRAC 24 and CMTS 12 which preclude filtering, or various forms ofvirtual tunneling and reverse virtual tunneling could be used tovirtually source upstream packets from CM 16. For more information onvirtual tunneling see Level 2 Tunneling Protocol (“L2TP”) orPoint-to-Point Tunneling Protocol (“PPTP”) in IETF draft documentsincorporated herein by reference by Kory Hamzeh, et. al (IETF draftdocuments are precursors to IETF RFCs and are works in progress).

CM 16 also forwards IP 54 datagrams destined to an IP 54 multicastaddress across cable network 14 or PSTN 22. CM 16 is configurable tokeep IP 54 multicast routing tables and to use group membershipprotocols. CM 16 is also capable of IP 54 tunneling upstream through thetelephony path. A CM 16 that wants to send a multicast packet across avirtual tunnel will prepend another IP 54 header, set the destinationaddress in the new header to be the unicast address of CMTS 12 at theother end of the tunnel, and set the IP 54 protocol field to be four,which means the next protocol is IP 54.

CMTS 12 at the other end of the virtual tunnel receives the packet,strips off the encapsulating IP 54 header, and forwards the packet asappropriate. A broadcast IP 54 capability is dependent upon theconfiguration of the direct linkage, if any, between TRAC 24 and CMTS12. CMTS 12, CM 16, and TRAC 24 are capable of routing IP 54 datagramsdestined to an IP 54 broadcast address which is across cable network 14or PSTN 22 if so configured. CM 16 is configurable for IP 54 broadcastdatagram filtering.

An operating environment for CM 16 of the present invention includes aprocessing system with at least one high speed Central Processing Unit(“CPU”) and a memory system. In accordance with the practices of personsskilled in the art of computer programming, the present invention isdescribed below with reference to acts and symbolic representations ofoperations that are performed by the processing system, unless indicatedotherwise. Such acts and operations are sometimes referred to as being“computer-executed”, or “CPU executed.”

It will be appreciated that the acts and symbolically representedoperations include the manipulation of electrical signals by the CPU.The electrical system represent data bits which cause a resultingtransformation or reduction of the electrical signal representation, andthe maintenance of data bits at memory locations in the memory system tothereby reconfigure or otherwise alter the CPU's operation, as well asother processing of signals. The memory locations where data bits aremaintained are physical locations that have particular electrical,magnetic, optical, or organic properties corresponding to the data bits.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, organic disks, and any othervolatile or non-volatile mass storage system readable by the CPU. Thecomputer readable medium includes cooperating or interconnected computerreadable media, which exist exclusively on the processing system or isdistributed among multiple interconnected processing systems that may belocal or remote to the processing system.

Initialization of a Cable Modem With Telephony Return

When CM 16 is initially powered on, if telephony return is being used,CM 16 will receive a Telephony Channel Descriptor (“TCD”) from CMTS 12that is used to provide dialing and access instructions on downstreamchannels via cable network 14. Information in the TCD is used by CM 16to connect to TRAC 24. The TCD is transmitted as a MAC managementmessage with a management type value of TRI_TCD at a periodic interval(e.g., every 2 seconds). To provide for flexibility, the TCD messageparameters are encoded in a Type/Length/Value (“TLV”) form. However,other encoding techniques could also be used. FIG. 3 is a block diagramillustrating a TCD message structure 70 with MAC 44 management header 72and Service Provider Descriptor(s) (“SPD”) 74 encoded in TLV format.SPDs 74 are compound TLV encodings that define telephony physical-layercharacteristics that are used by CM 16 to initiate a telephone call. SPD74 is a TLV-encoded data structure that contains sets of dialing andaccess parameters for CM 16 with telephony return. SPD 74 is containedwithin TCD message 70. There may be multiple SPD 74 encodings within asingle TCD message 70. There is at least one SPD 74 in TCD message 70.SPD 74 parameters are encoded as SPD-TLV tuples. SPD 74 contains theparameters shown in Table 1 and may contain optional vendor specificparameters. However, more or fewer parameters could also be used in SPD74.

TABLE 1 SPD 74 Parameter Description Factory Boolean value, if TRUE(1),indicates a Default SPD which should be used by CM 16. Flag Service Thisparameter includes the name of a Provider service provider. Format isstandard Name ASCII string composed of numbers and letters. TelephoneThese parameters contain telephone Numbers numbers that CM 16 uses toinitiate a telephony modem link during a login process. Connections areattempted in ascending numeric order (i.e., Phone Number 1, Phone Number2 . . . ). The SPD contains a valid telephony dial string as the primarydial string (Phone Number 1), secondary dial-strings are optional.Format is ASCII string(s) composed of: any sequence of numbers, pound“#” and star “*” keys and comma character “,” used to indicate a twosecond pause in dialing. Connection The number of sequential connectionThreshold failures before indicating connection failure. A dial attemptthat does not result in an answer and connection after no more than tenrings is considered a failure. The default value is one. Login Thiscontains a user name CM 16 will use User an authentication protocol overthe Name telephone link during the initialization procedure. Format is amonolithic sequence of alphanumeric characters in an ASCII stringcomposed of numbers and letters. Login This contains a password that CM16 will Password use during authentication over a telephone link duringthe initialization procedure. Format is a monolithic sequence ofalphanumeric characters in an ASCII string composed of numbers andletters. DHCP Boolean value, reserved to indicate that Authenticate CM16 uses a specific indicated DHCP 66 Server (see next parameter) for aDHCP 66 Client and BOOTP Relay Process when TRUE (one). The default isFALSE (zero) which allows any DHCP 66 Server. DHCP IP 54 address valueof a DHCP 66 Server Server CM 16 uses for DHCP 66 Client and BOOTP RelayProcess. If this attribute is present and DHCP 66 Authenticate attributeis TRUE(1). The default value is integer zero. RADIUS The realm name isa string that defines a Realm RADIUS server domain. Format is amonolithic sequence of alphanumeric characters in an ACSII stringcomposed of numbers and letters. PPP This parameter instructs thetelephone Authentication modem which authentication procedure to performover the telephone link. Demand This parameter indicates time (in Dialseconds) of inactive networking time that Timer will be allowed toelapse before hanging up a telephone connection at CM 16. If thisoptional parameter is not present, or set to zero, then the demand dialfeature is not activated. The default value is zero. Vendor Optionalvendor specific extensions. Specific Extensions

A Termination System Information (“TSI”) message is transmitted by CMTS12 at periodic intervals (e.g., every 2 seconds) to report CMTS 12information to CM 16 whether or not telephony return is used. The TSImessage is transmitted as a MAC 44 management message. The TSI providesa CMTS 12 boot record in a downstream channel to CM 16 via cable network14. Information in the TSI is used by CM 16 to obtain information aboutthe status of CMTS 12. The TSI message has a MAC 44 management typevalue of TRI_TSI.

FIG. 4 is a block diagram of a TSI message structure 76. TSI messagestructure 76 includes a MAC 44 management header 78, a downstreamchannel IP address 80, a registration IP address 82, a CMTS 12 boot time84, a downstream channel identifier 86, an epoch time 88 and vendorspecific TLV encoded data 90.

A description of the fields of TSI message 76 are shown in Table 2.However, more or fewer fields could also be used in TSI message 76.

TABLE 2 TSI 76 Parameter Description Downstream This field contains anIP 54 address of Channel CMTS 12 available on the downstream IP Address80 channel this message arrived on. Registration This field contains anIP 54 address IP Address 82 CM 16 sends its registration requestmessages to. This address MAY be the same as the Downstream Channel IP54 address. CMTS Boot Specifies an absolute-time of a CMTS Time 84 12recorded epoch. The clock setting for this epoch uses the current clocktime with an unspecified accuracy. Time is represented as a 32 bitbinary number. Downstream A downstream channel on which this Channelmessage has been transmitted. This ID 86 identifier is arbitrarilychosen by CMTS 12 and is unique within the MAC 44 layer. Epoch 88 Aninteger value that is incremented each time CMTS 12 is either re-initialized or performs address or routing table flush. Vendor Optionalvendor extensions may be Specific added as TLV encoded data. Extensions90

After receiving TCD 70 message and TSI message 76, CM 16 continues toestablish access to data network 28 (and resources on the network) byfirst dialing into TRAC 24 and establishing a telephony PPP 50 session.Upon the completion of a successful PPP 50 connection, CM 16 performsPPP Link Control Protocol (“LCP”) negotiation with TRAC 24. Once LCPnegotiation is complete, CM 16 requests Internet Protocol ControlProtocol (“IPCP”) address negotiation. For more information on IPCP seeRFC-1332 incorporated herein by reference. During IPCP negotiation, CM16 negotiates an IP 54 address with TRAC 24 for sending IP 54 datapacket responses back to data network 28 via TRAC 24.

When CM 16 has established an IP 54 link to TRAC 24, it begins“upstream” communications to CMTS 12 via DHCP layer 66 to complete avirtual data connection by attempting to discover network hostinterfaces available on CMTS 12 (e.g., IP 54 host interfaces for avirtual IP 54 connection). The virtual data connection allows CM 16 toreceive data from data network 28 via CMTS 12 and cable network 14, andsend return data to data network 28 via TRAC 24 and PSTN 22. CM 16 mustfirst determine an address of a host interface (e.g., an IP 54interface) available on CMTS 12 that can be used by data network 28 tosend data to CM 16. However, CM 16 has only a downstream connection fromCMTS 12 and has to obtain a connection address to data network 28 usingan upstream connection to TRAC 24.

Addressing Network Host Interfaces in the Data-over-cable System via theCable Modem

FIG. 5 is a flow diagram illustrating a method 92 for addressing networkhost interfaces in a data-over-cable system with telephony return via acable modem. Method 92 allows a cable modem to establish a virtual dataconnection to a data network. In method 92, multiple network devices areconnected to a first network with a downstream connection of a firstconnection type, and connected to a second network with an upstreamconnection of a second connection type. The first and second networksare connected to a third network with a third connection type.

At step 94, a selection input is received on a first network device fromthe first network over the downstream connection. The selection inputincludes a first connection address allowing the first network device tocommunicate with the first network via upstream connection to the secondnetwork. At step 96, a first message of a first type for a firstprotocol is created on the first network device having the firstconnection address from the selection input in a first message field.The first message is used to request a network host interface address onthe first network. The first connection address allows the first networkdevice to have the first message with the first message type forwardedto network host interfaces available on the first network via theupstream connection to the second network.

At step 98, the first network device sends the first message over theupstream connection to the second network. The second network uses thefirst address field in the first message to forward the first message toone or more network host interfaces available on first network at step100. Network host interfaces available on the first network that canprovide the services requested in first message send a second messagewith a second message type with a second connection address in a secondmessage field to the first network at step 102. The second connectionaddress allows the first network device to receive data packets from thethird network via a network host interface available on the firstnetwork. The first network forwards one or more second messages on thedownstream connection to the first network device at step 104.

The first network device selects a second connection address from one ofthe second messages from one of the one or more network host interfacesavailable on the first network at step 106 and establishes a virtualconnection from the third network to the first network device using thesecond connection address for the selected network host interface.

The virtual connection includes receiving data on the first network hostinterface on the first network from the third network and sending thedata over the downstream connection to the first network device. Thefirst network device sends data responses back to the third network overthe upstream connection to the second network, which forwards the datato the appropriate destination on the third network.

In one embodiment of the present invention, the data-over-cable systemis data-over-cable system 10, the first network device is CM 16, thefirst network is cable television network 14, the downstream connectionis a cable television connection. The second network is PSTN 22, theupstream connection is a telephony connection, the third network is datanetwork 28 (e.g., the Internet or an intranet) and the third type ofconnection is an IP 54 connection. The first and second connectionaddresses are IP 54 addresses. However, the present invention is notlimited to the network components and addresses described. Method 92allows CM 16 to determine an IP 54 network host interface addressavailable on CMTS 12 to receive IP 54 data packets from data network 28,thereby establishing a virtual IP 54 connection with data network 28.

After addressing network host interfaces using method 92, an exemplarydata path through cable system 10 is illustrated in Table 3. Howeverother data paths could also be used and the present invention is notlimited to the data paths shown in Table 3. For example, CM 16 may senddata upstream back through cable network 14 (e.g., CM 16 to cablenetwork 14 to CMTS 12) and not use PSTN 22 and the telephony returnupstream path.

TABLE 3 1. An IP 54 datagram from data network 28 destined for CM 16arrives on CMTS-NSI 32 and enters CMTS 12. 2. CMTS 12 encodes the IP 54datagram in a cable data frame, passes it to MAC 44 and transmits it“downstream” to RF interface 40 on CM 16 via cable network 14. 3. CM 16recognizes the encoded IP 54 datagram in MAC layer 44 received via RFinterface 40. 4. CM 16 responds to the cable data frame and encapsulatesa response IP 54 datagram in a PPP 50 frame and transmits it “upstream”with modem interface 48 via PSTN 22 to TRAC 24. 5. TRAC 24 decodes theIP 54 datagram and forwards it via TRAC-NSI 30 to a destination on datanetwork 28.

Dynamic Network Host Configuration on Data-over-cable System

As was illustrated in FIG. 2, CM 16 includes a Dynamic HostConfiguration Protocol (“DHCP”) layer 66, hereinafter DHCP 66. DHCP 66is used to provide configuration parameters to hosts on a network (e.g.,an IP 54 network). DHCP 66 consists of two components: a protocol fordelivering host-specific configuration parameters from a DHCP 66 serverto a host and a mechanism for allocation of network host addresses tohosts. DHCP 66 is built on a client-server model, where designated DHCP66 servers allocate network host addresses and deliver configurationparameters to dynamically configured network host clients.

FIG. 6 is a block diagram illustrating a DHCP 66 message structure 108.The format of DHCP 66 messages is based on the format of BOOTstrapProtocol (“BOOTP”) messages described in RFC-951 and RFC-1542incorporated herein by reference. From a network host client's point ofview, DHCP 66 is an extension of the BOOTP mechanism. This behaviorallows existing BOOTP clients to interoperate with DHCP 66 serverswithout requiring any change to network host the clients' BOOTPinitialization software. DHCP 66 provides persistent storage of networkparameters for network host clients.

To capture BOOTP relay agent behavior described as part of the BOOTPspecification and to allow interoperability of existing BOOTP clientswith DHCP 66 servers, DHCP 66 uses a BOOTP message format. Using BOOTPrelaying agents eliminates the necessity of having a DHCP 66 server oneach physical network segment.

DHCP 66 message structure 108 includes an operation code field 110(“op”), a hardware address type field 112 (“htype”), a hardware addresslength field 114 (“hlen”), a number of hops field 116 (“hops”), atransaction identifier field 118 (“xid”), a seconds elapsed time field120 (“secs”), a flags field 122 (“flags”), a client IP address field 124(“ciaddr”), a your IP address field 126 (“yiaddr”), a server IP addressfield 128 (“siaddr”), a gateway/relay agent IP address field 130(“giaddr”), a client hardware address field 132 (“chaddr”), an optionalserver name field 134 (“sname”), a boot file name 136 (“file”) and anoptional parameters field 138 (“options”). Descriptions for DHCP 66message 108 fields are shown in Table 4.

TABLE 4 DCHP 66 Parameter Description OP 110 Message op code/messagetype. 1 BOOTREQUEST, 2 = BOOTREPLY. HTYPE 112 Hardware address type(e.g., ‘1’ = 10 Mps Ethernet). HLEN 114 Hardware address length (e.g.‘6’ for 10 Mbps Ethernet). HOPS 116 Client sets to zero, optionally usedby relay-agents when booting via a relay- agent. XID 118 Transaction ID,a random number chosen by the client, used by the client and server toassociate messages and responses between a client and a server. SECS 120Filled in by client, seconds elapsed since client started trying toboot. FLAGS 122 Flags including a BROADCAST bit. CIADDR 124 Client IPaddress; filled in by client in DHCPREQUEST if verifying previouslyallocated configuration parameters. YIADDR 126 ‘Your’(client) IPaddress. SIADDR 128 IP 54 address of next server to use in bootstrap;returned in DHCPOFFER, DHCPACK and DHCPNAK by server. GIADDR 130 Gatewayrelay agent IP 54 address, used in booting via a relay-agent. CHADDRClient hardware address (e.g., MAC 132 layer 44 address). SNAME 134Optional server host name, null terminated string. FILE 136 Boot filename, terminated by a null string. OPTIONS Optional parameters. 138

The DHCP 66 message structure shown in FIG. 6 is used to discover IP 54and other network host interfaces in data-over-cable system 10. Anetwork host client (e.g., CM 16) uses DHCP 66 to acquire or verify anIP 54 address and network parameters whenever the network parameters mayhave changed. Table 5 illustrates a typical use of the DHCP 66 protocolto discover a network host interface from a network host client.

TABLE 5 1. A network host client broadcasts a DHCP 66 discover messageon its local physical subnet. The DHCP 66 discover message may includeoptions that suggest values for a network host interface address. BOOTPrelay agents may pass the message on to DHCP 66 servers not on the samephysical subnet. 2. DHCP servers may respond with a DHCPOFFER messagethat includes an available network address in the ‘yiaddr’ field (andother configuration parameters in DHCP 66 options) from a network hostinterface. DHCP 66 servers unicasts the DHCPOFFER message to the networkhost client (using the DHCP/BOOTP relay agent if necessary) if possible,or may broadcast the message to a broadcast address (preferably255.255.255.255) on the client's subnet. 3. The network host clientreceives one or more DHCPOFFER messages from one or more DHCP 66servers. The network host client may choose to wait for multipleresponses. 4. The network host client chooses one DHCP 66 server with anassociated network host interface from which to request configurationparameters, based on the configuration parameters offered in theDHCPOFFER messages.

Discovering Network Host Interfaces in the Data-over-cable System

The DHCP discovery process illustrated in table 5 will not work indata-over-cable system 10. CM 16 has only a downstream connection fromCMTS 12, which includes DHCP 66 servers, associated with network hostinterfaces available on CMTS 12. In a preferred embodiment of thepresent invention, CM 16 discovers network host interfaces via TRAC 24and PSTN 22 on an upstream connection.

The DHCP 66 addressing process shown in Table 5 was not originallyintended to discover network host interfaces in data-over-cable system10. CMTS 12 has DHCP 66 servers associated with network host interfaces(e.g., IP interfaces), but CM 16 only has as downstream connection fromCMTS 12. CM 16 has an upstream connection to TRAC 24, which has a DHCP66 layer. However; TRAC 24 does not have DHCP 66 servers, or directaccess to network host interfaces on CMTS 12.

FIGS. 7A and 7B are a flow diagram illustrating a method 140 fordiscovering network host interfaces in data-over-cable system 10. WhenCM 16 has established an IP 54 link to TRAC 24, it begins communicationswith CMTS 12 via DHCP 66 to complete a virtual IP 54 connection withdata network 28. However, to discover what IP 54 host interfaces mightbe available on CMTS 12, CM 16 has to communicate with CMTS 12 via PSTN22 and TRAC 24 since CM 16 only has a “downstream” cable channel fromCMTS 12.

At step 142 in FIG. 7A, after receiving a TSI message 76 from CMTS 12 ona downstream connection, CM 16 generates a DHCP discover(“DHCPDISCOVER”) message and sends it upstream via PSTN 22 to TRAC 22 todiscover what IP 54 interfaces are available on CMTS 12. The fields ofthe DHCP discover message are set as illustrated in Table 6. However,other field settings may also be used.

TABLE 6 DHCP 66 Parameter Description OP 110 Set to BOOTREQUEST. HTYPE112 Set to network type (e.g., one for 10 Mbps Ethernet). HLEN 114 Setto network length (e.g., six for 10 Mbps Ethernet) HOPS 116 Set to zero.FLAGS 122 Set BROADCAST bit to zero. CIADDR 124 If CM 16 has previouslybeen assigned an IP 54 address, the IP 54 address is placed in thisfield. If CM 16 has previously been assigned an IP 54 address by DHCP66, and also has been assigned an address via IPCP, CM 16 places theDHCP 66 IP 54 address in this field. GIADDR 130 CM 16 places theDownstream Channel IP 54 address 80 of CMTS 12 obtained in TSI message76 on a cable downstream channel in this field. CHADDR 132 CM 16 placesits 48-bit MAC 44 LAN address in this field.

The DHCPDISCOVER message is used to “discover” the existence of one ormore IP 54 host interfaces available on CMTS 12. DHCP 66 giaddr-field130 (FIG. 6) includes the downstream channel IP address 80 of CMTS 12obtained in TSI message 76 (e.g., the first message field from step 96of method 92). Using the downstream channel IP address 80 of CMTS 12obtained in TSI message 76 allows the DHCPDISCOVER message to beforwarded by TRAC 24 to DHCP 66 servers (i.e., protocol servers)associated with network host interfaces available on CMTS 12. If DHCP 66giaddr-field 130 (FIG. 6) in a DHCP message from a DHCP 66 client isnon-zero, the DHCP 66 server sends any return messages to a DHCP 66server port on a DHCP 66 relaying agent (e.g., CMTS 12) whose addressappears in DHCP 66 giaddr-field 130.

In a typical DHCP 66 discovery process the DHCP 66 giaddr-field 130 isset to zero. In a typical DHCP 66 discovery process the DHCP 66giaddr-field 130 is set to zero. However, in a preferred embodiment ofthe present invention, the giaddr-field 130 contains the IP address 80of CMTS 12. If DHCP 66 giaddr-field 130 is zero, the DHCP 66 client ison the same subnet as the DHCP 66 server, and the DHCP 66 server sendsany return messages to either the DHCP 66 client's network address, ifthat address was supplied in DHCP 66 ciaddr-field 124 (FIG. 6), or to aclient's hardware address specified in DHCP 66 chaddr-field 132 (FIG. 6)or to a local subnet broadcast address (e.g., 255.255.255.255).

At step 144, a DHCP 66 layer on TRAC 24 broadcasts the DHCPDISCOVERmessage on its local network leaving DHCP 66 giaddr-field 130 intactsince it already contains a non-zero value. TRAC's 24 local networkincludes connections to one or more DHCP 66 proxies (i.e., network hostinterface proxies). The DHCP 66 proxies accept DHCP 66 messagesoriginally from CM 16 destined for DHCP 66 servers connected to networkhost interfaces available on CMTS 12 since TRAC 24 has no direct accessto DCHP 66 servers associated with network host interfaces available onCMTS 12. DHCP 66 proxies are not used in a typical DHCP 66 discoveryprocess.

One or more DHCP 66 proxies on TRAC's 24 local network recognizes theDHCPDISCOVER message and forwards it to one or more DHCP 66 serversassociated with network host interfaces (e.g., IP 54 interfaces)available on CMTS 12 at step 146. Since DHCP 66 giaddr-field 130 (FIG.6) in the DHCPDISCOVER message sent by CM 16 is already non-zero (i.e.,contains the downstream IP address of CMTS 12), the DHCP 66 proxies alsoleave DHCP 66 giaddr-field 130 intact.

One or more DHCP 66 servers for network host interfaces (e.g., IP 54interfaces) available on CMTS 12 receive the DHCPDISCOVER message andgenerate a DHCP 66 offer message (“DHCPOFFER”) at step 148. The DHCP 66offer message is an offer of configuration parameters sent from networkhost interfaces to DHCP 66 servers and back to a network host client(e.g., CM 16) in response to a DHCPDISCOVER message. The DHCP 66 offermessage is sent with the message fields set as illustrated in Table 7.However, other field settings can also be used. DHCP 66 yiaddr-field 126(e.g., second message field from step 102 of method 92) contains an IP54 address for a network host interface available on CMTS 12 and usedfor receiving data packets from data network 28.

TABLE 7 DHCP 66 Parameter Description FLAGS 122 BROADCAST bit set tozero. YIADDR 126 IP 54 address from a network host interface to allow CM16 to receive data from data network 28 via a network host interfaceavailable on CMTS 12. SIADDR 128 An IP 54 address for a TFTP 64 serverto download configuration information for an interface host. CHADDR 132MAC 44 address of CM 16. SNAME 134 Optional DHCP 66 server identifierwith an interface host. FILE 136 A TFTP 64 configuration file name forCM 16.

DHCP 66 servers send the DHCPOFFER message to the address specified in66 giaddr-field 130 (i.e., CMTS 12) from the DHCPDISCOVER message ifassociated network host interfaces (e.g., IP 54 interfaces) can offerthe requested service (e.g., IP 54 service) to CM 16. The DHCPDISOVERmessage DHCP 66 giaddr-field 130 contains a downstream channel IPaddress 80 of CMTS 12 that was received by CM 16 in TSI message 76. Thisallows CMTS 12 to receive the DHCPOFFER messages from the DHCP 66servers and send them to CM 16 via a downstream channel on cable network14.

At step 150 in FIG. 7B, CMTS 12 receives one or more DHCPOFFER messagesfrom one or more DHCP 66 servers associated with the network hostinterfaces (e.g., IP 54 interfaces). CMTS 12 examines DHCP 66yiaddr-field 126 and DHCP 66 chaddr-field 132 in the DHCPOFFER messagesand sends the DHCPOFFER messages to CM 16 via cable network 14. DHCP 66yiaddr-field 126 contains an IP 54 address for a network host IP 54interface available on CMTS 12 and used for receiving IP 54 data packetsfrom data network 28. DHCP 66 chaddr-field 132 contains the MAC 44 layeraddress for CM 16 on a downstream cable channel from CMTS 12 via cablenetwork 14. CMTS 12 knows the location of CM 16 since it sent CM 16 aMAC 44 layer address in one or more initialization messages (e.g., TSImessage 76).

If a BROADCAST bit in flags field 124 is set to one, CMTS 12 sends theDHCPOFFER messages to a broadcast IP 54 address (e.g., 255.255.255.255)instead of the address specified in DHCP 66 yiaddr-field 126: DHCP 66chaddr-field 132 is still used to determine that MAC 44 layer address.If the BROADCAST bit in DHCP 66 flags field 122 is set, CMTS 12 does notupdate internal address or routing tables based upon DHCP 66yiaddr-field 126 and DHCP 66 chaddr-field 132 pair when a broadcastmessage is sent.

At step 152, CM 16 receives one or more DHCPOFFER messages from CMTS 12via cable network 14 on a downstream connection. At step 154, CM 16selects an offer for IP 54 service from one of the network hostinterfaces (e.g., an IP interfaces 54) available on CMTS 12 thatresponded to the DHCPDISOVER message sent at step 142 in FIG. 7A andestablishes a virtual IP 54 connection. The selected DHCPOFFER messagecontains a network host interface address (e.g., IP 54 address) in DHCP66 yiaddr-field 126 (FIG. 6). A cable modem acknowledges the selectednetwork host interface with DHCP 66 message sequence explained below.

After selecting and acknowledging a network host interface, CM 16 hasdiscovered an IP 54 interface address available on CMTS 12 forcompleting a virtual IP 54 connection with data network 28.Acknowledging a network host interface is explained below. The virtualIP 54 connection allows IP 54 data from data network 28 to be sent toCMTS 12 which forwards the IP 54 packets to CM 16 on a downstreamchannel via cable network 14. CM 16 sends response IP 54 packets back todata network 28 via PSTN 22 and TRAC 24.

FIG. 8 is a block diagram illustrating a data-over-cable system 156 forthe method illustrated in FIGS. 7A and 7B. Data-over-cable system 156includes DHCP 66 proxies 158, DHCP 66 servers 160 and associated NetworkHost Interfaces 162 available on CMTS 12. Multiple DHCP 66 proxies 158,DHCP 66 servers 160 and network host interfaces 162 are illustrated assingle boxes in FIG. 8. FIG. 8 also illustrates DHCP 66 proxies 158separate from TRAC 24. In one embodiment of the present invention, TRAC24 includes DHCP 66 proxy functionality and no separate DHCP 66 proxies158 are used. In such an embodiment, TRAC 24 forwards DHCP 66 messagesusing DHCP 66 giaddr-field 130 to DHCP 66 servers 160 available on CMTS12.

FIG. 9 is a block diagram illustrating a message flow 162 of method 140(FIGS. 7A and 7B).

Message flow 162 includes DHCP proxies 158 and DHCP servers 160illustrated in FIG. 8 Steps 142, 144, 146, 148, 150 and 154 of method140 (FIGS. 7A and 7B) are illustrated in FIG. 9. In one embodiment ofthe present invention, DHCP proxies 158 are not separate entities, butare included in TRAC 24. In such an embodiment, DHCP proxy services areprovided directly by TRAC 24.

Resolving Addresses for Network Host Interfaces

Since CM 16 receives multiple DHCPOFFER messages (Step 152FIG. 7B) CM 16resolves and acknowledges one offer from a selected network hostinterface. FIGS. 10A and 10B are a flow diagram illustrating a method166 for resolving and acknowledging host addresses in a data-over-cablesystem. Method 166 includes a first network device that is connected toa first network with a downstream connection of a first connection type,and connected to a second network with an upstream connection of asecond connection type. The first and second networks are connected to athird network with a third connection type. In one embodiment of thepresent invention, the first network device is CM 16, the first networkis cable network 14, the second network is PSTN 22 and the third networkis data network 28 (e.g., the Internet). The downstream connection is acable television connection, the upstream connection is a telephonyconnection, and the third connection is an IP connection.

Turning to FIG. 10A, one or more first messages are received on thefirst network device from the first network on the downstream connectionat step 168. The one or more first messages are offers from one or morenetwork host interfaces available on the first network to provide thefirst network device a connection to the third network. The firstnetwork device selects one of the network host interfaces using messagefields in one of the one or more first messages at step 170. The firstnetwork device creates a second message with a second message type toaccept the offered services from a selected network host interface atstep 172. The second message includes a connection address for the firstnetwork in a first message field and an identifier to identify theselected network host interface in a second message field.

The first network device sends the second message over the upstreamconnection to the second network at step 174. The second network usesthe first message field in the second message to forward the secondmessage to the one or more network host interfaces available on firstnetwork at step 176.

A network host interface available on the first network identified insecond message field in the second message from the first network devicerecognizes an identifier for the network host interface at 178 in FIG.10B. The selected network host interface sends a third message with athird message type to the first network at step 180. The third messageis an acknowledgment for the first network device that the selectednetwork host interface received the second message from the firstnetwork device. The first network stores a connection address for theselected network interface in one or more tables on the first network atstep 182. The first network will forward data from the third network tothe first network device when it is received on the selected networkhost interface using the connection address in the one or more routingtables. The first network forwards the third message to the firstnetwork device on the downstream connection at step 184. The firstnetwork device receives the third message at step 186. The first networkand the first network device have the necessary addresses for a virtualconnection that allows data to be sent from the third network to anetwork host interface on the first network, and from the first networkover the downstream connection to the first network device. Method 166accomplishes resolving network interface hosts addresses from a cablemodem in a data-over-cable with telephony return.

Method 166 of the present invention is used in data-over-cable system 10with telephony return. However, the present invention is not limited todata-over-cable system 10 with telephony return and can be used indata-over-cable system 10 without telephony return by using an upstreamcable channel instead of an upstream telephony channel.

FIGS. 11A and 11B are a flow diagram illustrating a method 188 forresolving discovered host addresses in data-over-cable system 10 withtelephony return. At step 190 in FIG. 11A, CM 16 receives one or moreDHCPOFFER messages from one or more DHCP 66 servers associated with oneor more network host interfaces (e.g., at step 168 in method 166). Theone or more DHCPOFFER messages include DHCP 66 fields set as illustratedin Table 7 above. However, other field settings could also be used. Atstep 192, CM 16 selects one of the DHCPOFFER messages (see also, step170 in method 166). At step 194, CM 16 creates a DHCP 66 request message(“DHCPREQUEST”) message to request the services offered by a networkhost interface selected at step 192. The fields of the DHCP requestmessage are set as illustrated in Table 8. However, other field settingsmay also be used.

TABLE 8 DHCP 66 Parameter Description OP 110 Set to BOOTREQUEST. HTYPE112 Set to network type (e.g., one for 10 Mbps Ethernet). HLEN 114 Setto network length (e.g., six for 10 Mbps Ethernet) HOPS 116 Set to zero.FLAGS 118 Set BROADCAST bit to zero. CIADDR 124 If CM 16 has previouslybeen assigned an IP address, the IP address is placed in this field. IfCM 16 has previously been assigned an IP address by DHCP 66, and alsohas been assigned an address via IPCP, CM 16 places the DHCP 66 IP 54address in this field. YIADDR 126 IP 54 address sent from the selectednetwork interface host in DCHPOFFER message GIADDR 130 CM 16 places theDownstream Channel IP 54 address 80 CMTS 12 obtained in TSI message 76on a cable downstream channel in this field. CHADDR 132 CM 16 places its48-bit MAC 44 LAN address in this field. SNAME 134 DHCP 66 serveridentifier for the selected network interface host

The DHCPREQUEST message is used to “request” services from the selectedIP 54 host interface available on CMTS 12 using a DHCP 66 serverassociated with the selected network host interface. DHCP 66giaddr-field 130 (FIG. 6) includes the downstream channel IP address 80for CMTS 12 obtained in TSI message 76 (e.g., the first message-fieldfrom step 172 of method 166). Putting the downstream channel IP address80 obtained in TSI message 76 allows the DHCPREQUEST message to beforwarded by TRAC 24 to DCHP 66 servers associated with network hostinterfaces available on CMTS 12. DHCP 66 giaddr-field 126 contains anidentifier (second message field, step 172 in method 166) DHCP 66sname-field 134 contains a DHCP 66 server identifier associated with theselected network host interface.

If DHCP 66 giaddr-field 130 in a DHCP message from a DHCP 66 client isnon-zero, a DHCP 66 server sends any return messages to a DHCP 66 serverport on a DHCP 66 relaying agent (e.g., CMTS 12) whose address appearsin DHCP 66 giaddr-field 130. If DHCP 66 giaddr-field 130 is zero, theDHCP 66 client is on the same subnet as the DHCP 66 server, and the DHCP66 server sends any return messages to either the DHCP 66 client'snetwork address, if that address was supplied in DHCP 66 ciaddr-field124, or to the client's hardware address specified in DHCP 66chaddr-field 132 or to the local subnet broadcast address.

Returning to FIG. 11A at step 196, CM 16 sends the DHCPREQUEST messageon the upstream connection to TRAC 24 via PSTN 22. At step 198, a DHCP66 layer on TRAC 24 broadcasts the DHCPREQUEST message on its localnetwork leaving DHCP 66 giaddr-field 130 intact since it alreadycontains a non-zero value. TRAC's 24 local network includes connectionsto one or more DHCP 66 proxies. The DHCP 66 proxies accept DHCP 66messages originally from CM 16 destined for DHCP 66 servers associatedwith network host interfaces available on CMTS 12. In another embodimentof the present invention, TRAC 24 provides the DHCP 66 proxyfunctionality, and no separate DHCP 66 proxies are used.

The one or more DHCP 66 proxies on TRAC's 24 local network messageforwards the DHCPOFFER to one or more of the DHCP 66 servers associatedwith network host interfaces (e.g., IP 54 interfaces) available on CMTS12 at step 200 in FIG. 11B. Since DHCP 66 giaddr-field 130 in theDHCPDISCOVER message sent by CM 16 is already non-zero (i.e., containsthe downstream IP address of CMTS 12), the DHCP 66 proxies leave DHCP 66giaddr-field 130 intact.

One or more DHCP 66 servers for the selected network host interfaces(e.g., IP 54 interface) available on CMTS 12 receives the DHCPOFFERmessage at step 202. A selected DHCP 66 server recognizes a DHCP 66server identifier in DHCP 66 sname-field 134 or the IP 54 address thatwas sent in the DCHPOFFER message in the DHCP 66 yiaddr-field 126 fromthe DHCPREQUST message as being for the selected DHCP 66 server.

The selected DHCP 66 server associated with network host interfaceselected by CM 16 in the DHCPREQUEST message creates and sends a DCHP 66acknowledgment message (“DHCPACK”) to CMTS 12 at step 204. The DHCPACKmessage is sent with the message fields set as illustrated in Table 9.However, other field settings can also be used. DHCP 66 yiaddr-fieldagain contains the IP 54 address for the selected network host interfaceavailable on CMTS 12 for receiving data packets from data network 28.

TABLE 9 DHCP 66 Parameter Description FLAGS 122 Set a BROADCAST bit tozero. YIADDR 126 IP 54 address for the selected network host interfaceto allow CM 16 to receive data from data network 28. SIADDR 128 An IP 54address for a TFTP 64 server to download configuration information foran interface host. CHADDR 132 MAC 44 address of CM 16. SNAME 134 DHCP 66server identifier associated with the selected network host interface.FILE 136 A configuration file name for an network interface host.

The selected DHCP 66 server sends the DHCACK message to the addressspecified in DHCP 66 giaddr-field 130 from the DHCPREQUEST message to CM16 to verify the selected network host interface (e.g., IP 54 interface)will offer the requested service (e.g., IP 54 service).

At step 206, CMTS 12 receives the DHCPACK message from the selected DHCP66 server associated with the selected network host interface IP 54address(e.g., IP 54 interface). CMTS 12 examines DHCP 66 yiaddr-field126 and DHCP 66 chaddr-field 132 in the DHCPACK message. DHCP 66yiaddr-field 126 contains an IP 54 address for a network host IP 54interface available on CMTS 12 and used for receiving IP 54 data packetsfrom data network 28 for CM 16. DHCP 66 chaddr-field 132 contains theMAC 44 layer address for CM 16 on a downstream cable channel from CMTS12 via cable network 14.

CMTS 12 updates an Address Resolution Protocol (“ARP”) table and otherrouting tables on CMTS 12 to reflect the addresses in DHCP 66yiaddr-field 126 and DHCP 66 chaddr-field 132 at step 208. As is knownin the art, ARP allows a gateway such as CMTS 12 to forward anydatagrams from a data network such as data network 28 it receives forhosts such as CM 16. ARP is defined in RFC-826, incorporated herein byreference. CMTS 12 stores a pair of network address values in the ARPtable, the IP 54 address of the selected network host interface fromDHCP 66 yiaddr-field 126 and a Network Point of Attachment (“NPA”)address. In a preferred embodiment of the present invention, The NPAaddress is a MAC 44 layer address for CM 16 via a downstream cablechannel. The IP/NPA address pair are stored in local routing tables withthe IP/NPA addresses of hosts (e.g., CMs 16) that are attached to cablenetwork 14.

At step 210, CMTS 12 sends the DHCPACK message to CM 16 via cablenetwork 14. At step 212, CM 16 receives the DHCPACK message, and alongwith CMTS 12 has addresses for a virtual connection between data network28 and CM 16. When data packets arrive on the IP 54 address for theselected host interface they are sent to CMTS 12 and CMTS 12 forwardsthem using a NPA (i.e., MAC 44 address) from the routing tables on adownstream channel via cable network 14 to CM 16.

If a BROADCAST bit in flags field 124 is set to one in the DHCPACK, CMTS12 sends the DHCPACK messages to a broadcast IP 54 address (e.g.,255.255.255.255). DHCP 66 chaddr-field 132 is still used to determinethat MAC layer address. If the BROADCAST bit in flags field 122 is set,CMTS 12 does not update the ARP table or offer routing tables based uponDHCP 66 yiaddr-field 126 and DHCP 66 chaddr-field 132 pair when abroadcast message is sent.

FIG. 12 is a block diagram illustrating the message flow 214 of themethod 188 illustrated in FIGS. 11A and 11B. Message flow 214 includesDHCP proxies 158 and DHCP servers 160 illustrated in FIG. 8. Methodsteps 194, 196, 198, 204, 208, 210and 212 of method 188 (FIGS. 11A and11B) are illustrated in FIG. 12. In one embodiment of the presentinvention, DHCP proxies 158 are not separate entities, but are includedin TRAC 24. In such an embodiment, DHCP proxy services are provideddirectly by TRAC 24.

After method 188, CMTS 12 has a valid IP/MAC address pair in one or moreaddress routing tables including an ARP table to forward IP 54 datapackets from data network 28 to CM 16, thereby creating a virtual IP 54data path to/from CM 16 as was illustrated in method 92 (FIG. 5) andTable 3. CM 16 has necessary parameters to proceed to the next phase ofinitialization, a download of a configuration file via TFTP 64. Once CM16 has received the configuration file and has been initialized, itregisters with CMTS 12 and is ready to receive data from data network14.

In the event that CM 16 is not compatible with the configuration of thenetwork host interface received in the DHCPACK message, CM 16 maygenerate a DHCP 66 decline message (“DHCPDECLINE”) and transmit it toTRAC 24 via PSTN 22. A DHCP 66 layer in TRAC 24 forwards the DHCPDECLINEmessage to CMTS 12. Upon seeing a DHCPDECLINE message, CMTS 12 flushesits ARP tables and routing tables to remove the now invalid IP/MACpairing. If an IP 54 address for a network host interface is returnedthat is different from the IP 54 address sent by CM 16 in theDCHCPREQUEST message, CM 16 uses the IP 54 address it receives in theDHCPACK message as the IP 54 address of the selected network hostinterface for receiving data from data network 28.

The present invention is described with respect to, but is not limitedto a data-over-cable-system with telephony return. Method 188 can alsobe used with a cable modem that has a two-way connection (i.e., upstreamand downstream) to cable network 14 and CMTS 12. In adata-over-cable-system without telephony return, CM 16 would broadcastthe DHCPREQUEST message to one or more DHCP 66 servers associated withone or more network host interfaces available on CMTS 12 using anupstream connection on data network 14 including the IP 54 address ofCMTS 12 in DHCP 66 giaddr-field 130. Method 188 accomplishes resolvingaddresses for network interface hosts from a cable modem in adata-over-cable with or without telephony return, and without extensionsto the existing DHCP protocol.

CPE Initialization in a Data-over-cable System

CPE 18 also uses DHCP 66 to generate requests to obtain IP 54 addressesto allow CPE 18 to also receive data from data network 28 via CM 16. Ina preferred embodiment of the present invention, CM 16 functions as astandard BOOTP relay agent/DHCP Proxy 158 to facilitate CPE's 18 accessto DHCP 66 server 160. FIGS. 13A and 13B are a flow diagram illustratinga method 216 for obtaining addresses for customer premise equipment. CM16 and CMTS 12 use information from method 214 to construct IP 54routing and ARP table entries for network host interfaces 162 providingdata to CMCI 20 and to CPE 18.

Method 216 in FIGS. 13A and 13B includes a data-over-cable system withtelephony return and first network device with a second network devicefor connecting the first network device to a first network with adownstream connection of a first connection type, and for connecting toa second network with an upstream connection of a second connectiontype. The first and second networks are connected to a third networkwith a third connection type.

In one embodiment of the present invention, data-over-cable system withtelephony return is data-over-cable system 10 with the first networkdevice CPE 18 and the second network device CM 16. The first network iscable television network 14, the downstream connection is a cabletelevision connection, the second network is PSTN 22, the upstreamconnection is a telephony connection, the third network is data network28 (e.g., the Internet or an intranet) and the third type of connectionis an IP 54 connection. However, the present invention is not limited tothe network components described and other network components may alsobe used. Method 216 allows CPE 18 to determine an IP 54 network hostinterface address available on CMTS 12 to receive IP 54 data packetsfrom data network 54, thereby establishing a virtual IP 54 connectionwith data network 28 via CM 16.

Returning to FIG. 13A at step 218, a first message of a first type(e.g., a DHCP 66 discover message) with a first message field for afirst connection is created on the first network device. The firstmessage is used to discover a network host interface address on thefirst network to allow a virtual connection to the third network.

At step 220, the first network device sends the first message to thesecond network device. The second network device checks the firstmessage field at step 222. If the first message field is zero, thesecond network device puts its own connection address into the firstmessage field at step 224. The second network device connection addressallows the messages from network host interfaces on the first network toreturn messages to the second network device attached to the firstnetwork device. If the first message field is non-zero, the secondnetwork device does not alter the first message field since there couldbe a relay agent attached to the first network device that may set thefirst connection address field.

At step 226, the second network device forwards the first message to aconnection address over the upstream connection to the second network.In one embodiment of the present invention, the connection address is anIP broadcast address (e.g., 255.255.255.255). However, other connectionaddresses can also be used.

The second network uses the first connection address in the firstmessage field in the first message to forward the first message to oneor more network host interfaces (e.g., IP 54 network host interfaces)available on first network at step 228. One or more network hostinterfaces available on the first network that can provide the servicesrequested in first message send a second message with a second messagetype with a second connection address in a second message field to thefirst network at step 230 in FIG. 13B. The second connection addressallows the first network device to receive data packets from the thirdnetwork via a network host interface on the first network. The firstnetwork forwards the one or more second messages on the downstreamconnection to the second network device at step 232. The second networkdevice forwards the one or more second messages to the first networkdevice at step 234. The first network device selects one of the one ormore network host interfaces on the first network using the one or moresecond messages at step 236. This allows a virtual connection to beestablished between the third network and the first network device viathe selected network host interface on the first network and the secondnetwork device.

FIGS. 14A and 14B are a flow diagram illustrating a method 240 forresolving addresses for the network host interface selected by a firstnetwork device to create a virtual connection to the third network.Turning to FIG. 14A, at step 240 one or more second messages arereceived with a second message type on the first network device from thesecond network device from the first network on a downstream connectionat step 242. The one or more second messages are offers from one or moreprotocol servers associated with one or more network host interfacesavailable on the first network to provide the first network device aconnection to the third network. The first network device selects one ofthe network host interfaces using one of the one or more second messagesat step 244. The first network device creates a third message with athird message type to accept the offered services from the selectednetwork host interface at step 246. The third message includes aconnection address for the first network in a first message field and anidentifier to identify the selected network host interface in a secondmessage field. At step 248, first network device equipment sends thethird message to the second network device.

The second network device sends the third message over the upstreamconnection to the second network at step 250. The second network usesthe first message field in the third message to forward the thirdmessage to the one or more network host interfaces available on firstnetwork at step 252.

A network host interface available on the first network identified insecond message field in the third message from the first network devicerecognizes an identifier for the selected network host interface at step254 in FIG. 14B. The selected network host interface sends a fourthmessage with a fourth message type to the first network at step 256. Thefourth message is an acknowledgment for the first network device thatthe selected network host interface received the third message. Thefourth message includes a second connection address in a third messagefield. The second connection address is a connection address for theselected network host interface. The first network stores the connectionaddress for the selected network interface from the third message in oneor more routing tables (e.g., an ARP table) on the first network at step258. The first network will forward data from the third network to thefirst network device via the second network device when it is receivedon the selected network host interface using the connection address fromthe third message field. The first network forwards the fourth messageto the second network device on the downstream connection at step 260.The second network device receives the fourth message and stores theconnection address from the third message field for the selected networkinterface in one or more routing tables on the second network device atstep 262. The connection address for the selected network interfaceallows the second network device to forward data from the third networksent by the selected network interface to the customer premiseequipment.

At step 264, the second network device forward the fourth message to thefirst network device. At step 266, the first network device establishesa virtual connection between the third network and the first networkdevice.

After step 266, the first network, the second network device and thefirst network device have the necessary connection addresses for avirtual connection that allows data to be sent from the third network toa network host interface on the first network, and from the firstnetwork over the downstream connection to the second network and then tothe first network device. In one embodiment of the present invention,method 240 accomplishes resolving network interface hosts addresses fromcustomer premise equipment with a cable modem in a data-over-cable withtelephony return without extensions to the existing DHCP protocol.

Methods 216 and 240 of the present invention are used in data-over-cablesystem 10 with telephony return with CM 16 and CPE 18. However, thepresent invention is not limited to data-over-cable system 10 withtelephony return and can be used in data-over-cable system 10 withouttelephony return by using an upstream cable channel instead of anupstream telephony channel.

FIGS. 15A and 15B are a flow diagram illustrating a method 268 foraddressing network host interfaces from CPE 18. At step 270 in FIG. 15A,CPE 18 generates a DHCPDISCOVER message broadcasts the DHCPDISCOVERmessage on its local network with the fields set as illustrated in Table6 above with addresses for CPE 18 instead of CM 16. However, more orfewer field could also be set. CM 16 receives the DHCPDISCOVER as astandard BOOTP relay agent at step 272. The DHCP DISCOVER message has aMAC 44 layer address for CPE 18 in DHCP 66 chaddr-field 132, which CM 16stores in one or more routing tables. As a BOOTP relay agent, the CM 16checks the DHCP 66 giaddr-field 130 (FIG. 6) at step 274. If DHCP 66giaddr-field 130 is set to zero, CM 16 put its IP 54 address into DHCP66 giaddr-field 130 at step 276.

If DHCP 66 giaddr-field 130 is non-zero, CM 16 does not alter DHCP 66giaddr-field 130 since there could be another BOOTP relay agent attachedto CPE 18 which may have already set DHCP 66 giaddr-field 130. Any BOOTPrelay agent attached to CPE 18 would have also have acquired its IP 54address from using a DCHP 66 discovery process (e.g., FIG. 12).

Returning to FIG. 15A, at step 278, CM 16 broadcasts the DHCPDISCOVERmessage to a broadcast address via PSTN 22 to TRAC 24. In one embodimentof the present invention, the a broadcast address is an IP 54 broadcastaddress (e.g., 255.255.255.255). At step 280, one or more DHCP 66proxies 158 associated with TRAC 24, recognize the DHCPDISOVER message,and forward it to one or more DHCP 66 servers 160 associated with one ormore network host interfaces 162 available on CMTS 12. Since DHCP 66giaddr-field 130 is already non-zero, the DHCP proxies leave DHCP 66giaddr-field 130 intact. In another embodiment of the present invention,TRAC 24 includes DCHP 66 proxy 158 functionality and no separate DHCP 66proxies 158 are used.

At step 282 in FIG. 15B, the one or more DHCP servers 160 receive theDHCPDISCOVER message from one or more DHCP proxies, and generate one ormore DHCPOFFER messages to offer connection services for one or morenetwork host interfaces 162 available on CMTS 12 with the fields set asillustrated in Table 7. The one or more DHCP servers 160 send the one ormore DHCPOFFER messages to the address specified in DHCP 66 giaddr-field130 (e.g., CM 16 or a BOOTP relay agent on CPE 18), which is an IP 54address already contained in an ARP or other routing table in CMTS 12.Since CMTS 12 also functions as a relay agent for the one or more DHCPservers 160, the one or more DHCPOFFER messages are received on CMTS 12at step 284.

CMTS 12 examines DHCP 66 yiaddr-field 126 and DHCP 66 giaddr-field 130in the DHCPOFFER messages, and sends the DHCPOFFER messages down cablenetwork 14 to IP 54 address specified in the giaddr-field 130. The MAC44 address for CM 16 is obtained through a look-up of the hardwareaddress associated with DHCP 66 chaddr-field 130. If the BROADCAST bitin DHCP 66 flags-field 122 is set to one, CMTS 12 sends the DHCPOFFERmessage to a broadcast IP 54 address (e.g., 255.255.255.255), instead ofthe address specified in DHCP 66 yiaddr-field 126. CMTS 12 does notupdate its ARP or other routing tables based upon the broadcast DCHP 66yiaddr-field 126 DHCP 66 chaddr-field 132 address pair.

Returning to FIG. 15B, CM 16 receives the one or more DHCPOFFER messagesand forwards them to CPE 18 at step 286. CM 16 uses the MAC 44 addressspecified determined by DHCP 66 chaddr-field 132 look-up in its routingtables to find the address of CPE 18 even if the BROADCAST bit in DHCP66 flags-field 122 is set. At step 290, CPE 18 receives the one or moreDHCPOFFER messages from CM 16. At step 292, CPE 18 selects one of theDHCPOFFER messages to allow a virtual connection to be establishedbetween data network 28 and CPE 18. Method 266 accomplishes addressingnetwork interface hosts from CPE 18 in data-over-cable system 10 withoutextensions to the existing DHCP protocol.

FIGS. 16A and 16B are a flow diagram illustrating a method 294 forresolving network host interfaces from CPE 18. At step 296, CPE 18receives the one or more DHCPOFFER messages from one or more DHCP 66servers associated with one or more network host interface available onCMTS 12. At step 298, CPE 18 chooses one offer of services from aselected network host interface. At step 300, CPE 18 generates aDHCPREQUEST message with the fields set as illustrated in Table 8 abovewith addresses for CPE 18 instead of CM 16. However, more or fewerfields could also be set. At step 302, CPE 18 sends the DHCPREQUESTmessage to CM 16. At step 304, CM 16 forwards the message to TRAC 24 viaPSTN 22.

At step 306, a DHCP 66 layer on TRAC 24 broadcasts the DHCPREQUESTmessage on its local network leaving DHCP 66 giaddr-field 130 intactsince it already contains a non-zero value. TRAC's 24 local networkincludes connections to one or more DHCP 66 proxies. The DHCP 66 proxiesaccept DHCP 66 messages originally from CPE 18 destined for DHCP 66servers associated with network host interfaces available on CMTS 12. Inanother embodiment of the present invention, TRAC 24 provides the DHCP66 proxy functionality, and no separate DHCP 66 proxies are used.

One or more DHCP 66 proxies on TRAC's 24 local network recognize theDHCPOFFER message and forward it to one or more of the DHCP 66 serversassociated with network host interfaces (e.g., IP 54 interfaces)available on CMTS 12 at step 308 in FIG. 16B. Since DHCP 66 giaddr-field130 in the DHCPDISCOVER message sent by CPE 18 is already non-zero, theDHCP 66 proxies leave DHCP 66 giaddr-field 130 intact.

One or more DHCP 66 servers for the selected network host interfaces(e.g., IP 54 interface) available on CMTS 12 receive the DHCPOFFERmessage at step 310. A selected DHCP 66 server recognizes a DHCP 66server identifier in DHCP 66 sname-field 134 or the IP 54 address thatwas sent in the DCHPOFFER message in the DHCP 66 yiaddr-field 126 fromthe DHCPREQUST message for the selected DHCP 66 server.

The selected DHCP 66 server associated with network host interfaceselected by CPE 18 in the DHCPREQUEST message creates and sends a DCHPacknowledgment message (“DHCPACK”) to CMTS 12 at step 312 using the DHCP66 giaddr-field 130. The DHCPACK message is sent with the message fieldsset as illustrated in Table 9. However, other field settings can also beused. DHCP 66 yiaddr-field contains the IP 54 address for the selectednetwork host interface available on CMTS 12 for receiving data packetsfrom data network 28 for CPE 18.

At step 314, CMTS 12 receives the DHCPACK message. CMTS 12 examines theDHCP 66 giaddr-field 130 and looks up that IP address in its ARP tablefor an associated MAC 44 address. This is a MAC 44 address for CM 16,which sent the DHCPREQUEST message from CPE 18. CMTS 12 uses the MAC 44address associated with the DHCP 66 giaddr-field 130 and the DHCP 66yiaddr-field 126 to update its routing and ARP tables reflecting thisaddress pairing at step 316. At step 318, CMTS 12 sends the DHCPACKmessage on a downstream channel on cable network 14 to the IP 54 and MAC44 addresses, respectively (i.e., to CM 16). If the BROADCAST bit in theDHCP 66 flags-field 122 is set to one, CMTS 12 sends the DHCPACK messageto a broadcast IP 54 address (e.g., 255.255.255.255), instead of theaddress specified in the DHCP 66 yiaddr-field 126. CMTS 12 uses the MAC44 address associated with the DHCP 66 chaddr-field 130 even if theBROADCAST bit is set.

CM 16 receives the DHCPACK message. It examines the DHCP 66 yiaddr-field126 and chaddr-field 132, and updates its routing table and an ARProuting table to reflect the address pairing at step 320. At step 322,CM 16 sends the DHCPACK message to CPE 18 via CMCI 20 at IP 54 and MAC44 addresses respectively from its routing tables. If the BROADCAST bitin the DHCP 66 flags-field 122 is set to one, CM 16 sends the downstreampacket to a broadcast IP 54 address (e.g., 255.255.255.255), instead ofthe address specified in DHCP 66 yiaddr-field 126. CM 16 uses the MAC 44address specified in DHCP 66 chaddr-field 132 even if the BROADCAST bitis set to located CPE 18. At step 324, CPE 18 receives the DHCPACK fromCM 16 and has established a virtual connection to data network 28.

In the event that CPE 18 is not compatible with the configurationreceived in the DHCPACK message, CPE 18 may generate a DHCP 66 decline(“DHCPDECLINE”) message and send it to CM 16. CM 16 will transmit theDHCPDECLINE message up the PPP 50 link via PSTN 22 to TRAC 24. On seeinga DHCPDECLINE message TRAC 24 sends a unicast copy of the message toCMTS 12. CM 16 and CMTS 12 examine the DHCP 66 yiaddr-field 126 andgiaddr-field 130, and update their routing and ARP tables to flush anyinvalid pairings.

Upon completion of methods 266 and 292, CM 16 CMTS 12 have valid IP/MACaddress pairings in their routing and ARP tables. These tables store thesame set of IP 54 addresses, but does not associate them with the sameMAC 44 addresses. This is because CMTS 12 resolves all CPE 18 IP 54addresses to the MAC 44 address of a corresponding CM 16. The CMs 16, onother hand, are able to address the respective MAC 44 addresses of theirCPEs 18. This also allows DHCP 66 clients associated with CPE 18 tofunction normally since the addressing that is done in CM 16 and CMTS 12is transparent to CPE 18 hosts.

FIG. 17 is a block diagram illustrating a message flow 326 for methods268 and 294 in FIGS. 15A, 15B, and 16A and 16B. Message flow 326illustrates a message flow for methods 268 and 294, for adata-over-cable system with and without telephony return. In anotherembodiment of the present invention, CM 16 forwards requests from CPE 18via an upstream connection on cable network 14 to DHCP servers 160associated with one or more network host interfaces available on CMTS12.

Method 268 and 294 accomplishes resolving addresses for networkinterface hosts from customer premise equipment in a data-over-cablewith or without telephony return without extensions to the existing DHCPprotocol. Methods 268 and 294 of the present invention are used indata-over-cable system 10 with telephony return. However, the presentinvention is not limited to data-over-cable system 10 with telephonyreturn and can be used in data-over-cable system 10 without telephonyreturn by using an upstream cable channel instead of an upstreamtelephony channel.

Using the initialization sequences described above (FIG. 12), CM 16obtains configuration parameters at the beginning of every session ondata-over-cable system 10. CM 16 uses an IP 54 address and aconfiguration file name obtained in a DHCP 66 response message duringinitialization to establish connections to data-over-cable system 10. CM16 initiates a TFTP 64 exchange to request the configuration fileobtained in the DHCP 66 response message. The configuration file nameobtained by CM 16 includes required configuration parameters forinitialization and additional parameters for Class-of-Service andQuality-of-Service. The configuration parameters obtained in therequired configuration file and additional parameters are sent from CM16 to CMTS 12 in a registration message.

Quality-of-service in a Data-over-cable System

During initialization, individual cable modems request upstream anddownstream connections with different Class-of-Service (“CoS”) andQuality of Service (“QoS”) to/from CMTS 12 on cable network 14. Iftelephony return is used, then cable modems request downstream CoS andQoS connections from CMTS 12 on cable network 14. As is known in theart, CoS provides a reliable (e.g., error free, in sequence, with noloss of duplication) transport facility independent of the QoS. QoScollectively specifies the performance of the network service that adevice expects on a network. The CoS and QoS connections are requestedwith a registration message sent from CM 16 to CMTS 12.

FIG. 18 is a block diagram illustrating data-over-cable system 330 usedfor a preferred embodiment of the present invention. Data-over-cablesystem 330 is similar to the data over cable system illustrated in FIG.8. However, FIG. 18 illustrates a QoS server 332 used to determinewhether CMTS 12 has available bandwidth to provide a specificquality-of-service request to a CM 16. A quality-of-service bandwidthrequest includes bandwidth allocated for CoS, QoS and other relatedparameters and is hereinafter called “quality-of-service “bandwidthrequest”. QoS server 332 handles CoS, QoS and other related parametersand is hereinafter called a “QoS server” for the sake of simplicity. QoSserver 332 maintains multiple quality-of-service identifiers allocatedwith a database 334 for CoS and other QoS designations. The multiplequality-of-service identifiers are an indication of CoS, QoS and otherrelated parameters requested by CM 16 and are collectively called“quality-of-service identifiers” for the sake of simplicity. FIG. 18illustrates QoS server 332 separate from CMTS 12 in TRTS 26. However QoSserver 332 may also be integral to CMTS 12 (e.g., as a dedicated QoSprocess running on CMTS 12 or integrated into DHCP 66 server 160).

In addition to the configuration information from the configuration filesent to CMTS 12 by CM 16, one or more of Type-of-Service, FlowIdentification Definition, Service Identifier, Multi-cast group orNumber of CPEs configuration parameters may be added to the registrationrequest message to request a specific quality-of-service connection.However, more or fewer additional configuration parameters in differentformats could also be added to the registration request. CoS, QoS,Type-of-Service, Flow Identification Definition, Service IDentifier,Multi-cast group and Number of CPEs configuration parameters in TLVformat are illustrated in Tables 10-20. However, other values andlayouts could also be used.

Table 10 illustrates exemplary CoS (e.g., class one and class two) inTLV format. However, more or fewer classes of service along with othervalues could also be used. CoS parameters include maximum downstreamdata rates in bits-per-second (“bps”), maximum upstream data rate inbps, upstream channel priority, guaranteed minimum data rates in bps,guaranteed maximum data rate in bps and other parameters. Table 10illustrates CoS values as a TLV Value sub-type, Length Value format.However, other layouts could also be used.

TABLE 10 Value Description of Type Length (sub)type Length Value Value 428 1 1 1 CoS-1 4 28 2 4 10,000,000 Maximum forward rate of 10 Mbps 4 283 4 2,000,000 Maximum return rate of 2 Mbps 4 28 4 1 5 Return pathpriority of 5 4 28 5 4 64,000 Minimum guaranteed rate of 64 kbps 4 28 62 100 Maximum transmission burst of 100 mini-slots 4 28 1 1 2 CoS-2 4 282 4 5,000,000 Maximum forward rate of 5 Mbps 4 28 3 4 1,000,000 Maximumreturn rate of 1 Mbps 4 28 4 1 3 Return priority path of 3 4 28 5 432,000 Minimum guaranteed rate of 32 kbps 4 28 6 2 50 Maximumtransmission burst of 50 mini-slots

QoS parameters include transit delay expected to deliver data to aspecific destination, the level of protection from unauthorizedmonitoring or modification of data, cost for delivery of data, expectedresidual error probability, the relative priority associated with thedata and other parameters.

Table 11 illustrates QoS parameters as Flow Identifiers in TLV format.However, more fewer flow identifiers could also be used.

TABLE 11 Type/Subtype Length Description of Value Ax N Flow ClassDefinition Header A0 4 Flow Class Identifier A1 1 Flow Type A2 1Ethernet precedence and TOS A3 1 ATM flow subtype A4 6 Minimum number ofbytes/sec A5 6 Maximum number of bytes/sec A6 N Cell Error Ratio A7 NCell Loss Ratio A8 N Cell Mis-insertion Rate A9 N Mean Cell TransferDelay A10 N Cell Variation Delay  A11-A127 N Reserved A128-A255 N VendorSpecific

Table 12 illustrates Type-Of-Service sub-TLV information for QoSparameters. However, more or fewer TOS parameters could also be used.

TABLE 12 Type of Service Decimal (TOS) Bit-0 Bit-1 Bit-2 Bit-3 ValueMaximize 1 0 0 0 1 Delay Maximize 0 1 0 0 2 Through- put Maximize 0 0 10 4 Reliability Minimize 0 0 0 1 8 Cost Normal 0 0 0 0 0 Service

Table 13 illustrates Flow Identifier Values (Type A0, Table 11).However, more or fewer flow identifier values could also be used.

TABLE 13 Flow Identifier Value (4-bytes) Definition of Value 0 Thepacket is to be sent to the network without any special treatment. 1 Thepacket is to be sent to the network using a precedence (i.e., priority)and TOS. 2 . . . 255 Reserved.

Table 14 illustrates Flow type (Type A1, Table 11). However, more orfewer flow types could also be used.

TABLE 14 Flow type Definition 1 IP 54 2 ATM 3 . . . 255 Reserved

Table 15 illustrates Asynchronous Transport Mode (“ATM”) Flow sub-type(Type A3, Table 11). However, more or fewer ATM flow sub-types couldalso be used.

Table 15 ATM Flow Sub-type Definition 1 Universal Bit Rate (“UBR”) 2Constant Bit Rate (“CBR”) 3 Adaptable Bit Rate (“ABR”) 4 Variable BitRate (“VBR”)

CM 16 adds Service IDentifiers (“SIDs”) to the registration message sentto CMTS 12. SIDs provide device identification, QoS and CoS management.In particular, they are integral to bandwidth identification. A SIDdefines a particular mapping between CM 12 and CMTS 16. This mapping isthe basis on which bandwidth is allocated to CM 16 by CMTS 12 CoS andQoS is implemented. Within MAC 44, SIDs are unique and CMTS 12 mayassign one or more SIDs to each CM 16, corresponding to the CoS or QoSrequired by CM 16. Table 16 illustrates SID parameters in TLV format.However, more or fewer SID parameters could also be used.

TABLE 16 Type/Subtype Length Description of Value Default Value Bx NService Identifier Header B0 1 Service Identifier Type 0 B1 1 Number ofService 1 Identifier's (SIDs) to be given with this definition B2 4 FlowIdentifier for 0 SIDs B3 4 CoS for SIDs 0 B4 4 Source IP CM's IP 54address 54 address B5 4 Source IP 54 address 255.255.255.255 mask B6 4Destination IP 54 255.255.255.255 address B7 4 Destination IP 54255.255.255.255 address mask B8 1 IP Protocol Type 256 B9 4 Source Port(Start) 0 B10 4 Source Port (End) 65,535 B11 4 Destination Port 0(Start) B12 4 Destination Port (End) 65,535 B13 1 Precedence and TOS 0B14 1 Precedence and TOS 255 Mask B15 N Multicast group Null string ″″definition B16 4 Protocol Type 0xffffffff B17-B127 N Reserved B128-B255N Vendor Specific

Table 17 illustrates multicast and unicast Service Identifier Type (TypeB0, Table 16) values. However, more or fewer service identifier typescould also be used.

TABLE 17 Service Identifier Type Value Value Definition 1 Outgoingunicast from CM 16 2 Outgoing multicast from CM 16 3 Incoming unicast toCM 16 8 Outgoing multicast to CM 16

Table 18 illustrates IP Protocol Type values (Type B8, Table 16).However, more or fewer IP protocol types could also be used.

TABLE 18 IP Protocol Type Value Value Definition 1 ICMP 56 2Transmission Control Protocol (“TCP”) 4 UDP 60 256  Any Protocol

Table 19 illustrates Protocol Type values (Type B16, Table 16). However,more or fewer protocol types could also be used.

TABLE 18 Protocol Type Value Value Definition 0 No Protocols Allowed 1IP 54 2 Internet Packet eXchange (“IPX”) 4 Appletalk 8 ATM 0xffffffffAll protocols allowed

Table 20 illustrates the Number of CPEs 18 that can connect to CM 16during a session. However, more or fewer number of CPEs could also beused.

TABLE 20 Type Length Description of Value Default H 2 Number of CPEs 181 = CPE 18 or that can connect to 0xffffffff = any CM 16 during a numberof CPEs 18 session

FIG. 19 is a flow diagram illustrating a method 336 for providingquality of service for a network device in a data over-cable-system.Method 336 includes receiving a request on a first network device from asecond network device to establish a connection between the secondnetwork device and a third network device with a specificquality-of-service at step 338. The quality-of-service request includesbandwidth for CoS, QoS and other parameters. The first network devicedetermines whether the second network device has enough availablebandwidth to establish the connection to the third network device withthe specific quality-of-service requested at step 340. The bandwidthdetermination includes a bandwidth determination required for CoS, QoSand other parameters. If the first network device has enough bandwidthto establish the connection to the third network device with thespecific quality-of-service at step 340, a bandwidth required for thespecific quality-of-service is subtracted from an available bandwidthfor the second network device at step 342. At step 344, aquality-of-service identifier is assigned to the specificquality-of-service bandwidth requested. The quality-of-serviceidentifier is assigned based on bandwidth required CoS, QoS and otherparameters. The assigned quality-of-service identifier is saved on thefirst network device at step 346. The assigned quality-of-serviceidentifier is sent to the second network device indicating the secondnetwork device has enough bandwidth to allow the connection with thespecific quality-of-service requested at step 348. If the first networkdevice does not have enough available bandwidth to establish theconnection to the third network device with the specificquality-of-service requested by the third network device at step 340, arejection is sent to the first network device at step 350.

In a preferred embodiment of the present invention, the first networkdevice is QoS server 332, the second network device is CMTS 12 and thethird network device is CM 16. The quality-of-service identifiers areimplemented as additional SIDs (Table 16). In another embodiment of thepresent invention, the quality-of-service identifiers are notimplemented as additional SIDs (Table 16), but are implemented as a newtype of identifier used in data-over-cable system 330. However, thepresent invention is not limited to these network devices orquality-of-service identifiers and other network devices andquality-of-service identifiers could also be used. Method 336 moveshandling and allocation of bandwidth for CM 16 from CMTS 12 to QoSserver 332.

FIG. 20 is flow diagram illustrating a method 352 for providingquality-of-service to a cable modem. At step 354, QoS server 332receives a request from CMTS 12 to establish a connection between CMTS12 and CM 16 with a specific quality-of-service requested by CM 16(e.g., for CoS, QoS and other parameters in Tables 10-20). At step 356,QoS server 332 determines whether CMTS 12 has enough available bandwidthto establish the connection to CM 16 with the specificquality-of-service requested by CM 16. If CMTS 12 has enough bandwidth(e.g., for CoS, QoS and other parameters in tables 10-20) to establishthe connection to CM 16 with the specific quality-of-service requestedby CM 16, a bandwidth required for the specific quality-of-servicerequested by CM 16 is subtracted from an available bandwidth for CMTS 12at step 358. At step 360, a quality-of-service identifier is assigned tothe specific quality-of-service bandwidth requested by CM 16. Theassigned quality-of-service identifier is saved on QoS server at step362. At step 364, The assigned quality-of-service identifier sourceidentifier is sent to CMTS 12 indicating that CMTS 12 has enoughbandwidth to allow the connection with the specific quality-of-servicerequested by CM 16. If CMTS 12 does not have enough available bandwidthto establish the connection to CM 16 with the specificquality-of-service requested by CM 16 at step 340, a rejection is sentto CMTS 12 at step 365.

FIG. 21 is a flow diagram illustrating a method 366 for determiningquality-of-service on a network device. At step 368, a request isreceived on a first network device from a second network device, therequest including a request to establish a connection between the secondnetwork device and the first network device with a specificquality-of-service. At step 370, the request is sent to a third networkdevice to determine whether the second network device has enoughbandwidth to establish the connection to the first network device withthe specific quality-of-service requested. At step 372, a response isreceived from the third network device. At step 374, a test is conductedto determine whether the response contains a quality-of-serviceidentifier for the specific quality-of-service requested by the firstnetwork device. The quality-of-service identifier indicates that thesecond network device has enough available bandwidth to establish theconnection. If the response contains a quality-of-service identifier, atstep 376 the second network device creates a connection to the firstnetwork device with the specific quality-of-service requested. If theresponse does not contain a quality-of-service identifier, a rejectionis sent from the first network device to the second network device atstep 378.

In a preferred embodiment of the present invention, the first networkdevice is CMTS 12, the second network device is CM 16 and the thirdnetwork device is QoS server 332. However, other network devices couldalso be used and the present invention is not limited to these networkdevices.

FIG. 22 is a flow diagram illustrating a method 378 for determiningquality-of-service from CMTS 12. At step 380, a request is received onCMTS 12 from CM 16, the request including a request to establish aconnection between CMTS 12 and CM 16 with a specific quality-of-servicerequested by CM 16. At step 382, the request is sent to QoS server 332to determine whether CMTS 12 has enough bandwidth to establish theconnection to CM 16 with the specific quality-of-service requested by CM16. At step 384, a response is received on CMTS 12 from QoS server 332.At step 386, a test is conducted to determine whether the responsecontains a quality-of-service identifier for the specificquality-of-service requested by CM 16. The quality-of- serviceidentifier indicates that CMTS 12 has enough available bandwidth toestablish the connection. If the response contains a quality-of-serviceidentifier, at step 376 CMTS 12 creates a connection to CM 16 with thespecific quality-of-service requested by CM 16. If the response does notcontain a quality-of-service identifier, a rejection is sent from CMTS12 to CM 16 at step 378.

Table 21 illustrates an exemplary registration message sent to CMTS 12by CM 16. CMTS 12 sends the information from Table 21 to QoS server 332using method 352. QoS server 332 returns a quality-of-service identifierif CMTS 12 has enough bandwidth to service the request.

TABLE 21 Value Description of Type Length (sub)type Length Value Value 428 1 1 1 (CoS-1) (Table 10) 4 28 2 4 10,000,000 Maximum forward rate of10 Mbps 4 28 3 4 2,000,000 Maximum return rate of 2 Mbps 4 28 4 1 5Return path priority of 5 4 28 5 4 64,000 Minimum guaranteed rate of 64kbps 4 28 6 2 100 Maximum transmission burst of 100 mini-slots A 28 0 41 QoS Flow Class-1 (Table 12) A 28 2 1 8 (Table 11) A 28 1 1 1 IP 54(Table 14) A 28 7 1 1 1000:1 A 28 10  1 5 1 millisecond

Table 22 illustrates exemplary quality-of-service identifiers assignedby QoS server 332. However, other layouts and TLV parameters may beused.

TABLE 22 Value/ Type Length (sub)type Length Value Description 1 7 1 1 1 CoS-1 (e.g., Table 10) QoS 7 2 2 128 First QoS identifier for serviceclass-1 1 7 1 1  2 CoS-2 (e.g., Table 10) QoS 7 2 2 244 First QoSidentifier for service class-2 . . . . . . . . . . . . . . . . . . 1 7 11 N CoS-N QoS 7 2 2 345 QoS identifier for service class-N

Quality-of-service identifiers allocated by QoS server 332 are assignedand grouped according to the specific quality-of-service requestsreceived. For example, if a first CM 16 made a quality-of-servicerequest for CoS-1 illustrated in Table 20, QoS server 332 assigns aquality-of-service identifier of 128 to the request. If a second CM 16made a quality-of-service request for CoS-1, QoS may assign aquality-of-service identifier of 129 to the request. Other requests forquality-of-service identifiers for CoS-1 continue with 130.

However, if a third CM 16 made a quality-of-service request for CoS-2,QoS assigns a quality-of-service identifier starting at 244. Thisallocation allows QoS server 332 to group similar quality-of-servicerequests in a range of quality-of-service identifiers. For example,CoS-1 quality-of-service requests in the range 128-243, CoS-2quality-of-service requests in the range 244-300, etc. Table 23illustrates an exemplary grouping of quality-of-service requests.However, other groupings could also be used.

TABLE 23 QoS identifier Description CoS-1 Identifiers 12 Mbps (Table 10)128 CoS-1 #1 129 CoS-1 #2 CoS-2 Identifiers  6 Mbps (Table 10) 244 CoS-2#1

In one embodiment of the present invention, QoS server determinesbandwidth available on CMTS 12 with quality-of-service identifiersassigned to CMTS 12 and subtracting QoS bandwidth from an availablebandwidth. For example, if CMTS 12 has a total available bandwidth of1000 Mbps and has allocated ten CoS-1 quality-of-service requests at 12Mbps each, and 5 CoS-2 quality-of-service requests at 6 Mbps each, thenCMTS 12 has 850 Mbps of available bandwidth remaining (1000Mbps−(10*12+5*6)Mbps=850 Mbps).

When CM 16 disconnects from CMTS 12, CMTS 12 sends a release message toQoS server 332 including a quality-of-service identifier for a requestedquality-of-service connection by CM 16 that is being disconnected. QoSserver 332 deletes the quality-of-service identifier (e.g., from Table23) and adds a corresponding bandwidth associated with thequality-of-service identifier back into an available bandwidth for CMTS12.

A preferred embodiment of the present invention is illustrated withinteractions between CM 16, CMTS 12 and QoS 332. However, the presentinvention can also be practiced by making QoS requests directly to QoSserver 332 directly from CM 16. In such an embodiment, CM 16 sends aquality-of-service identifier returned from QoS server 332 in aregistration message to CMTS 12. CMTS 12 allocates a connection with aspecific quality of service requested by CM 16 when a quality-of-serviceidentifier is detected in the registration message, indicating thatCMTS12 has available bandwidth for the specific quality-of-servicerequest.

A preferred embodiment of the present invention is described for oneCMTS 12 as is illustrated in FIG. 18. However, QoS server 332 can alsobe used to handle and balance CoS, QoS and other requests among multipleCMTS 12 (not illustrated in FIG. 18). For example, if CM 16 makes aconnection request with a requested quality-of-service for a first CMTS12, and first CMTS 12 does not have the available bandwidth, QoS server332 directs a second CMTS with available bandwidth to respond to theconnection request from CM 16.

A system for a preferred embodiment of the present invention includes aquality-of-service server (e.g., QoS server 332), for determiningwhether a first network device has enough available bandwidth toestablish a connection to a second network device with a specificquality-of-service requested by the second network device. Thequality-of-service server provides support for class-of-service,quality-of-service and other parameters. The system also includesmultiple quality-of-service identifiers, for identifying a transmissionbandwidth required for a specific quality-of-service requested by asecond network device, wherein a value for a quality-of-serviceidentifier is determined by the quality-of-service bandwidth requestedby class-of-service, quality-of-service and other parameters. In apreferred embodiment of the present invention, the quality-of-serviceserver is QoS server 332, the first network device is CMTS 12 and thesecond network device is CM 16. However, the present invention is notlimited to these network devices and other network devices could also beused.

A preferred embodiment of the present invention offers severaladvantages over the prior art. CoS and QoS are handled and balanced indata-over-cable system 10 by QoS server 332. This relieves thecomputational burden from CMTS 12 and helps reduce or eliminate the needfor complex CoS and QoS software CMTS 12. QoS server 332 provides astandardized way of handling CoS and QoS requests for one or more CMTS12 and is easily adaptable for new CoS or QoS parameters.

It should be understood that the programs, processes, methods, systemsand apparatus described herein are not related or limited to anyparticular type of computer apparatus (hardware or software), unlessindicated otherwise. Various types of general purpose or specializedcomputer apparatus may be used with or perform operations in accordancewith the teachings described herein.

In view of the wide variety of embodiments to which the principles ofthe invention can be applied, it should be understood that theillustrated embodiments are exemplary only, and should not be taken aslimiting the scope of the present invention. For example, the steps ofthe flow diagrams may be taken in sequences other than those described,and more or fewer elements or component may be used in the blockdiagrams.

The claims should not be read as limited to the described order orelements unless stated to that effect. Therefore, all embodiments thatcome within the scope and spirit of the following claims and equivalentsthereto are claimed as the invention.

We claim:
 1. In a data-over-cable system with a plurality of networkdevices, a method for providing quality-of-service, the methodcomprising the following steps: receiving a request on a first networkdevice from a second network device to establish a connection betweenthe second network device and a third network device with a specificquality-of-service, wherein the request for a quality-of-serviceconnection request includes class-of-service and quality-of-serviceparameters; determining on the first network device whether the secondnetwork device has enough available bandwidth to establish thequality-of-service connection to the third network device with thespecific quality-of-service requested, and if so, subtracting abandwidth required for the specific quality-of-service requested fromthe available bandwidth for the second network device; assigning aquality-of-service identifier to the required quality-of-servicebandwidth; storing the assigned quality-of-service identifier on thefirst network device; and sending the assigned quality-of-serviceidentifier to the second network device, wherein the assignedquality-of-service identifier indicates that the second network devicehas enough bandwidth to establish the connection to the third networkdevice with the specific quality-of-service requested.
 2. A computerreadable medium having stored therein instructions for causing a centralprocessing unit to execute steps of the method of claim
 1. 3. The methodof claim 1 wherein the first network device is a quality-of-serviceserver, the second network device is a cable modem termination system,and the third network device is a cable modem.
 4. The method of claim 1,wherein the first network device is a quality-of-service server, thesecond network device is a cable modem, and the third network device isa cable modem termination system.
 5. The method of claim 1 furthercomprising: determining on the first network device whether the secondnetwork device has enough bandwidth to establish the connection to thethird network device with the specific quality-of-service requested, andif not, sending a rejection to the second network device indicating thatthere is not enough available bandwidth on the second network device toestablish a connection with the specific quality-of-service requested.6. The method of claim 1 further comprising: receiving a request on thefirst network device to release bandwidth for a specificquality-of-service connection, the request including aquality-of-service identifier; deleting the quality-of-serviceidentifier stored on the first network device; and adding a bandwidthreleased for the specific quality-of-service identified by thequality-of-service identifier to an available bandwidth for the secondnetwork device.
 7. The method of claim 1 wherein the determining stepincludes determining whether the second network device has enough usablebandwidth in the available bandwidth to guarantee the specificquality-of-service requested at a required transmission rate in theavailable bandwidth for the second network device.
 8. The method ofclaim 1 wherein the determining step includes determining whether thesecond network device has enough available bandwidth using a pluralityof quality-of-service identifiers stored on the first network device. 9.The method of claim 1 wherein the step of assigning a quality-of-serviceidentifier to specific quality-of-service requested includes assigningbandwidth for upstream and downstream channels for the connection fromthe second network device to the third network device.
 10. The method ofclaim 1 wherein the step of assigning a quality-of-service identifier tospecific quality-of-service requested includes assigning aquality-of-service identifier value based on a required transmissionbandwidth for the specific quality-of-service desired.
 11. The method ofclaim 1 wherein the storing step includes grouping quality-of-serviceidentifiers for quality-of-service requests requiring similartransmission bandwidths.
 12. The method of claim 1 wherein the step ofreceiving a request on a first network device includes receiving arequest from either the second network device or the third networkdevice.
 13. In a data-over-cable system with a plurality of networkdevices, a method of providing quality-of-service, the method comprisingthe following steps: receiving a request on a first network device froma second network device, the request including a request to establishconnection between the second network device and the first networkdevice with a specific quality-of-service requested; sending the requestto a third network device to determine whether the second network devicehas enough bandwidth to establish the connection to the first networkdevice with the specific quality-of-service requested; receiving aresponse from the third network device; determining whether the responsecontains a quality-of-service identifier for the specificquality-of-service requested, wherein the quality-of-service identifierindicates that the second network device has enough available bandwidthto establish the connection, and if the response contains aquality-of-service identifier, and if so, connecting the second networkdevice to the first network device with the specific quality-of-servicerequested.
 14. A computer readable medium having stored thereininstructions for causing a central processing unit to execute steps ofthe method of claim
 13. 15. The method of claim 13 wherein the firstnetwork device is a cable modem termination system, the second networkdevice is a cable modem, and the third network device is aquality-of-service server.
 16. The method of claim 13 wherein thequality-of-service identifier identifies a specific transmissionbandwidth required for the specific quality-of-service desired by thesecond network device and a value of quality-of-service identifier isdetermined by the specific quality-of-service bandwidth requested. 17.The method of claim 13 further comprising: determining whether theresponse contains a quality-of-service identifier for the specificquality-of-service requested by the first network device, and if not,rejecting the request for the connection between the first networkdevice and the second network device for the specific quality-of-servicerequested by the first network device.
 18. A system for providingquality-of-service connections, the system comprising:quality-of-service server, for determining whether a first networkdevice has enough available bandwidth to establish a connection to asecond network device with a specific quality-of-service requested bythe second network device, wherein the specific quality-of-servicerequested includes class-of-service and quality-of-service parameters;and plurality of quality-of-service identifiers, for identifying atransmission bandwidth required for a specific quality-of-servicerequested by a second network device, wherein a value for thequality-of-service identifier is determined by a quality-of-servicebandwidth requested with class-of-service and quality-of-serviceparameters.
 19. The system of claim 18 wherein the first network deviceis a cable modem termination system and the second network device is acable modem.
 20. The system of claim 18 wherein the quality-of-serviceserver determines whether the first network device has enough usablebandwidth to guarantee a specific quality-of-service requested by asecond network device at a guaranteed transmission rate in the bandwidthavailable for the first network device.
 21. In a data-over-cable systemwith a plurality of cable modems, a method for providingquality-of-service, the method comprising the following steps: sending arequest for a specific quality-of-service from a first network device toa second network device to determine whether a third network device hasenough bandwidth to establish a connection to the first network device;receiving a response from the second network device; and determiningwhether the response contains a quality-of-service identifier for thespecific quality-of-service requested by the first network device,wherein the quality-of-service identifier indicates that the secondnetwork device has enough available bandwidth to establish theconnection, and if the response contains a quality-of-serviceidentifier, sending the quality-of-service identifier from the firstnetwork device to the third network device.
 22. A computer readablemedium having stored therein instructions for causing a centralprocessing unit to execute the steps of the method of claim
 21. 23. Themethod of claim 21 wherein the first network device is a cable modem,the second network device is a quality-of-service server, and the thirdnetwork device is a cable modem termination system.
 24. The method ofclaim 21 further comprising: receiving the quality-of-service identifieron the third network device from the second network device; andestablishing a connection from the third network device to the firstnetwork device based on the specific quality-of-service requested by thefirst network device.
 25. In a data-over-cable system with a pluralityof cable modems, a method for providing quality-of-service, the methodcomprising the following steps: receiving a request on aquality-of-service server from a cable modem termination system, therequest including a request to establish a connection between the cablemodem termination system and a cable modem with a specificquality-of-service requested by the cable modem, wherein thequality-of-service request includes class-of-service andquality-of-service parameters; determining on the quality-of-serviceserver whether the cable modem termination system has enough bandwidthto establish the connection to the cable modem with the specificquality-of-service requested by the cable modem, and if so, subtractinga bandwidth required for the specific quality-of-service requested bythe cable modem from an available bandwidth for the cable modemtermination system; assigning a quality-of-service identifier to thespecific quality-of-service bandwidth requested by the cable modem;storing the assigned quality-of-service identifier on thequality-of-service server; and sending the assigned quality-of-serviceidentifier to the cable modem termination system, wherein thequality-of-service identifier indicates that the cable modem terminationsystem has enough available bandwidth to establish the connection to thecable modem.
 26. A computer readable medium have stored thereininstructions for causing a central processing unit to execute the stepsof the method of claim 25.